Chemical element
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A chemical element is a chemical substance that cannot be broken down into other substances by chemical reactions. The basic particle that constitutes a chemical element is the atom. Chemical elements are identified by the number of protons in the nuclei of their atoms,[1] known as the element's atomic number.[2] For example, oxygen has an atomic number of 8, meaning that each oxygen atom has 8 protons in its nucleus. Two or more atoms of the same element can combine to form molecules, in contrast to chemical compounds or mixtures, which contain atoms of different elements. Atoms can be transformed into different elements in nuclear reactions, which change an atom's atomic number.
Almost all of the
The history of the discovery and use of the elements began with primitive human societies that discovered native minerals like carbon, sulfur, copper and gold (though the concept of a chemical element was not yet understood). Attempts to classify materials such as these resulted in the concepts of classical elements, alchemy, and various similar theories throughout human history. Much of the modern understanding of elements developed from the work of Dmitri Mendeleev, a Russian chemist who published the first recognizable periodic table in 1869. This table organizes the elements by increasing atomic number into rows ("periods") in which the columns ("groups") share recurring ("periodic") physical and chemical properties. The periodic table summarizes various properties of the elements, allowing chemists to derive relationships between them and to make predictions about compounds and potential new ones.
By November 2016, the
Description
The lightest chemical elements are
Of the 94 naturally occurring elements, those with atomic numbers 1 through 82 each have at least one stable isotope (except for technetium, element 43 and promethium, element 61, which have no stable isotopes). Isotopes considered stable are those for which no radioactive decay has yet been observed. Elements with atomic numbers 83 through 94 are unstable to the point that radioactive decay of all isotopes can be detected. Some of these elements, notably bismuth (atomic number 83), thorium (atomic number 90), and uranium (atomic number 92), have one or more isotopes with half-lives long enough to survive as remnants of the explosive stellar nucleosynthesis that produced the heavy metals before the formation of our Solar System. At over 1.9×1019 years, over a billion times longer than the current estimated age of the universe, bismuth-209 (atomic number 83) has the longest known alpha decay half-life of any naturally occurring element, and is almost always considered on par with the 80 stable elements.[7][8] The very heaviest elements (those beyond plutonium, element 94) undergo radioactive decay with half-lives so short that they are not found in nature and must be synthesized.
There are now 118 known elements. In this context, "known" means observed well enough, even from just a few decay products, to have been differentiated from other elements.[9][10] Most recently, the synthesis of element 118 (since named oganesson) was reported in October 2006, and the synthesis of element 117 (tennessine) was reported in April 2010.[11][12] Of these 118 elements, 94 occur naturally on Earth. Six of these occur in extreme trace quantities: technetium, atomic number 43; promethium, number 61; astatine, number 85; francium, number 87; neptunium, number 93; and plutonium, number 94. These 94 elements have been detected in the universe at large, in the spectra of stars and also supernovae, where short-lived radioactive elements are newly being made. The first 94 elements have been detected directly on Earth as primordial nuclides present from the formation of the Solar System, or as naturally occurring fission or transmutation products of uranium and thorium.
The remaining 24 heavier elements, not found today either on Earth or in astronomical spectra, have been produced artificially: these are all radioactive, with very short half-lives; if any atoms of these elements were present at the formation of Earth, they are extremely likely, to the point of certainty, to have already decayed, and if present in novae have been in quantities too small to have been noted. Technetium was the first purportedly non-naturally occurring element synthesized, in 1937, although trace amounts of technetium have since been found in nature (and also the element may have been discovered naturally in 1925).[13] This pattern of artificial production and later natural discovery has been repeated with several other radioactive naturally occurring rare elements.[14]
Atomic number
The atomic number of an element is equal to the number of protons in each atom, and defines the element.[15] For example, all carbon atoms contain 6 protons in their atomic nucleus; so the atomic number of carbon is 6.[16] Carbon atoms may have different numbers of neutrons; atoms of the same element having different numbers of neutrons are known as isotopes of the element.[17]
The number of protons in the atomic nucleus also determines its
The symbol for atomic number is Z.
Isotopes
Isotopes are atoms of the same element (that is, with the same number of protons in their atomic nucleus), but having different numbers of neutrons. Thus, for example, there are three main isotopes of carbon. All carbon atoms have 6 protons in the nucleus, but they can have either 6, 7, or 8 neutrons. Since the mass numbers of these are 12, 13 and 14 respectively, the three isotopes of carbon are known as carbon-12, carbon-13, and carbon-14, often abbreviated to 12C, 13C, and 14C. Carbon in everyday life and in chemistry is a mixture of 12C (about 98.9%), 13C (about 1.1%) and about 1 atom per trillion of 14C.
Most (66 of 94) naturally occurring elements have more than one stable isotope. Except for the isotopes of hydrogen (which differ greatly from each other in relative mass—enough to cause chemical effects), the isotopes of a given element are chemically nearly indistinguishable.
All of the elements have some isotopes that are radioactive (radioisotopes), although not all of these radioisotopes occur naturally. The radioisotopes typically decay into other elements upon radiating an alpha or beta particle. If an element has isotopes that are not radioactive, these are termed "stable" isotopes. All of the known stable isotopes occur naturally (see primordial isotope). The many radioisotopes that are not found in nature have been characterized after being artificially made. Certain elements have no stable isotopes and are composed only of radioactive isotopes: specifically the elements without any stable isotopes are technetium (atomic number 43), promethium (atomic number 61), and all observed elements with atomic numbers greater than 82.
Of the 80 elements with at least one stable isotope, 26 have only one single stable isotope. The mean number of stable isotopes for the 80 stable elements is 3.1 stable isotopes per element. The largest number of stable isotopes that occur for a single element is 10 (for tin, element 50).
Isotopic mass and atomic mass
The mass number of an element, A, is the number of nucleons (protons and neutrons) in the atomic nucleus. Different isotopes of a given element are distinguished by their mass numbers, which are conventionally written as a superscript on the left hand side of the atomic symbol (e.g. 238U). The mass number is always a whole number and has units of "nucleons". For example, magnesium-24 (24 is the mass number) is an atom with 24 nucleons (12 protons and 12 neutrons).
Whereas the mass number simply counts the total number of neutrons and protons and is thus a natural (or whole) number, the
The standard atomic weight (commonly called "atomic weight") of an element is the average of the atomic masses of all the chemical element's isotopes as found in a particular environment, weighted by isotopic abundance, relative to the atomic mass unit. This number may be a fraction that is not close to a whole number. For example, the relative atomic mass of chlorine is 35.453 u, which differs greatly from a whole number as it is an average of about 76% chlorine-35 and 24% chlorine-37. Whenever a relative atomic mass value differs by more than 1% from a whole number, it is due to this averaging effect, as significant amounts of more than one isotope are naturally present in a sample of that element.
Chemically pure and isotopically pure
Chemists and nuclear scientists have different definitions of a pure element. In chemistry, a pure element means a substance whose atoms all (or in practice almost all) have the same atomic number, or number of protons. Nuclear scientists, however, define a pure element as one that consists of only one stable isotope.[18]
For example, a copper wire is 99.99% chemically pure if 99.99% of its atoms are copper, with 29 protons each. However it is not isotopically pure since ordinary copper consists of two stable isotopes, 69% 63Cu and 31% 65Cu, with different numbers of neutrons. However, a pure gold ingot would be both chemically and isotopically pure, since ordinary gold consists only of one isotope, 197Au.
Allotropes
Atoms of chemically pure elements may bond to each other chemically in more than one way, allowing the pure element to exist in multiple chemical structures (spatial arrangements of atoms), known as allotropes, which differ in their properties. For example, carbon can be found as diamond, which has a tetrahedral structure around each carbon atom; graphite, which has layers of carbon atoms with a hexagonal structure stacked on top of each other; graphene, which is a single layer of graphite that is very strong; fullerenes, which have nearly spherical shapes; and carbon nanotubes, which are tubes with a hexagonal structure (even these may differ from each other in electrical properties). The ability of an element to exist in one of many structural forms is known as 'allotropy'.
The reference state of an element is defined by convention, usually as the thermodynamically most stable allotrope and physical state at a pressure of 1 bar and a given temperature (typically at 298.15K). However, for phosphorus, the reference state is white phosphorus even though it is not the most stable allotrope. In thermochemistry, an element is defined to have an enthalpy of formation of zero in its reference state. For example, the reference state for carbon is graphite, because the structure of graphite is more stable than that of the other allotropes.
Properties
Several kinds of descriptive categorizations can be applied broadly to the elements, including consideration of their general physical and chemical properties, their states of matter under familiar conditions, their melting and boiling points, their densities, their crystal structures as solids, and their origins.
General properties
Several terms are commonly used to characterize the general physical and chemical properties of the chemical elements. A first distinction is between
A more refined classification is often shown in colored presentations of the periodic table. This system restricts the terms "metal" and "nonmetal" to only certain of the more broadly defined metals and nonmetals, adding additional terms for certain sets of the more broadly viewed metals and nonmetals. The version of this classification used in the periodic tables presented here includes:
States of matter
Another commonly used basic distinction among the elements is their state of matter (phase), whether solid, liquid, or gas, at a selected standard temperature and pressure (STP). Most of the elements are solids at conventional temperatures and atmospheric pressure, while several are gases. Only bromine and mercury are liquids at 0 degrees Celsius (32 degrees Fahrenheit) and normal atmospheric pressure; caesium and gallium are solids at that temperature, but melt at 28.4 °C (83.2 °F) and 29.8 °C (85.6 °F), respectively.
Melting and boiling points
Melting and boiling points, typically expressed in degrees Celsius at a pressure of one atmosphere, are commonly used in characterizing the various elements. While known for most elements, either or both of these measurements is still undetermined for some of the radioactive elements available in only tiny quantities. Since helium remains a liquid even at absolute zero at atmospheric pressure, it has only a boiling point, and not a melting point, in conventional presentations.
Densities
The density at selected standard temperature and pressure (STP) is frequently used in characterizing the elements. Density is often expressed in grams per cubic centimetre (g/cm3). Since several elements are gases at commonly encountered temperatures, their densities are usually stated for their gaseous forms; when liquefied or solidified, the gaseous elements have densities similar to those of the other elements.
When an element has allotropes with different densities, one representative allotrope is typically selected in summary presentations, while densities for each allotrope can be stated where more detail is provided. For example, the three familiar allotropes of carbon (amorphous carbon, graphite, and diamond) have densities of 1.8–2.1, 2.267, and 3.515 g/cm3, respectively.
Crystal structures
The elements studied to date as solid samples have eight kinds of
Occurrence and origin on Earth
Chemical elements may also be categorized by their origin on Earth, with the first 94 considered naturally occurring, while those with atomic numbers beyond 94 have only been produced artificially as the synthetic products of human-made nuclear reactions.
Of the 94 naturally occurring elements, 83 are considered primordial and either
No radioactive decay has been observed for elements with atomic numbers 1 through 82, except 43 (technetium) and 61 (promethium). Observationally stable isotopes of some elements (such as tungsten and lead), however, are predicted to be slightly radioactive with very long half-lives:[19] for example, the half-lives predicted for the observationally stable lead isotopes range from 1035 to 10189 years. Elements with atomic numbers 43, 61, and 83 through 94 are unstable enough that their radioactive decay can readily be detected. Three of these elements, bismuth (element 83), thorium (element 90), and uranium (element 92) have one or more isotopes with half-lives long enough to survive as remnants of the explosive stellar nucleosynthesis that produced the heavy elements before the formation of the Solar System. For example, at over 1.9×1019 years, over a billion times longer than the current estimated age of the universe, bismuth-209 has the longest known alpha decay half-life of any naturally occurring element.[7][8] The very heaviest 24 elements (those beyond plutonium, element 94) undergo radioactive decay with short half-lives and cannot be produced as daughters of longer-lived elements, and thus are not known to occur in nature at all.
Periodic table
Group | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Hydrogen & alkali metals |
Alkaline earth metals | Triels | Tetrels | Pnictogens | Chalcogens | Halogens | Noble gases | ||||||||||||
Period |
|||||||||||||||||||
2 | |||||||||||||||||||
3 | |||||||||||||||||||
4 | |||||||||||||||||||
5 | |||||||||||||||||||
6 | |||||||||||||||||||
7 | |||||||||||||||||||
- Ca: 40.078 — Abridged value (uncertainty omitted here)[21]
- Po: [209] — mass number of the most stable isotope
The properties of the chemical elements are often summarized using the periodic table, which powerfully and elegantly organizes the elements by increasing atomic number into rows ("periods") in which the columns ("groups") share recurring ("periodic") physical and chemical properties. The current standard table contains 118 confirmed elements as of 2021.
Although earlier precursors to this presentation exist, its invention is generally credited to the Russian chemist Dmitri Mendeleev in 1869, who intended the table to illustrate recurring trends in the properties of the elements. The layout of the table has been refined and extended over time as new elements have been discovered and new theoretical models have been developed to explain chemical behavior.
Use of the periodic table is now ubiquitous within the academic discipline of chemistry, providing an extremely useful framework to classify, systematize and compare all the many different forms of chemical behavior. The table has also found wide application in physics, geology, biology, materials science, engineering, agriculture, medicine, nutrition, environmental health, and astronomy. Its principles are especially important in chemical engineering.
Nomenclature and symbols
The various chemical elements are formally identified by their unique atomic numbers, by their accepted names, and by their
Atomic numbers
The known elements have atomic numbers from 1 through 118, conventionally presented as Arabic numerals. Since the elements can be uniquely sequenced by atomic number, conventionally from lowest to highest (as in a periodic table), sets of elements are sometimes specified by such notation as "through", "beyond", or "from ... through", as in "through iron", "beyond uranium", or "from lanthanum through lutetium". The terms "light" and "heavy" are sometimes also used informally to indicate relative atomic numbers (not densities), as in "lighter than carbon" or "heavier than lead", although technically the weight or mass of atoms of an element (their atomic weights or atomic masses) do not always increase monotonically with their atomic numbers.
Element names
The naming of various substances now known as elements precedes the
For purposes of international communication and trade, the
According to IUPAC, chemical elements are not proper nouns in English; consequently, the full name of an element is not routinely capitalized in English, even if derived from a proper noun, as in californium and einsteinium. Isotope names of chemical elements are also uncapitalized if written out, e.g., carbon-12 or uranium-235. Chemical element symbols (such as Cf for californium and Es for einsteinium), are always capitalized (see below).
In the second half of the twentieth century, physics laboratories became able to produce nuclei of chemical elements with half-lives too short for an appreciable amount of them to exist at any time. These are also named by IUPAC, which generally adopts the name chosen by the discoverer. This practice can lead to the controversial question of which research group actually discovered an element, a question that delayed the naming of elements with atomic number of 104 and higher for a considerable amount of time. (See
Precursors of such controversies involved the nationalistic namings of elements in the late 19th century. For example, lutetium was named in reference to Paris, France. The Germans were reluctant to relinquish naming rights to the French, often calling it cassiopeium. Similarly, the British discoverer of niobium originally named it columbium, in reference to the New World. It was used extensively as such by American publications before the international standardization (in 1950).
Chemical symbols
Specific chemical elements
Before chemistry became a science, alchemists had designed arcane symbols for both metals and common compounds. These were however used as abbreviations in diagrams or procedures; there was no concept of atoms combining to form molecules. With his advances in the atomic theory of matter, John Dalton devised his own simpler symbols, based on circles, to depict molecules.
The current system of chemical notation was invented by
Since Latin was the common language of science at Berzelius's time, his symbols were abbreviations based on the Latin names of elements (they may be Classical Latin names of elementary substances known since antiquity or Neo-Latin coinages for later elements). The symbols are not followed by a period (full stop) as with abbreviations. In most cases, Latin names of elements as used by Berzelius have the same roots as modern English names. For example, hydrogen has the chemical symbol "H" after the Neo-Latin hydrogenium, which has the same Ancient Greek roots as English hydrogen. However, in eleven cases Latin (as used by Berzelius) and English names of elements have different roots. Eight of them are the seven metals of antiquity and a metalloid also known since antiquity: "Fe" (Latin ferrum) for iron, "Hg" (Latin hydrargyrum) for mercury, "Sn" (Latin stannum) for tin, "Au" (Latin aurum) for gold, "Ag" (Latin argentum) for silver, "Pb" (Latin plumbum) for lead, "Cu" (Latin cuprum) for copper, and "Sb" (Latin stibium) for antimony. The three other mismatches between Neo-Latin (as used by Berzelius) and English names are "Na" (Neo-Latin natrium) for sodium, "K" (Neo-Latin kalium) for potassium, and "W" (Neo-Latin wolframium) for tungsten. These mismatches came from different suggestings of naming the elements in the Modern era. Initially Berzelius suggested "So" and "Po" for sodium and potassium, but he changed the symbols to "Na" and "K" later in the same year.
Elements discovered after 1814 were also assigned unique chemical symbols, based on the name of the element. The use of Latin as the universal language of science was fading, but chemical names of newly discovered elements came to be borrowed from language to language without or with little modifications. Symbols of elements discovered after 1814 match their names in English, French (ignoring the acute accent on ⟨é⟩), and German (although German in many cases allows alternative spellings with ⟨k⟩ or ⟨z⟩ instead of ⟨c⟩: e. g., the name of caesium may be spelled Caesium, Cäsium, or Zäsium in German, but its symbol is always "Cs"). Other languages sometimes modify element name spellings: Spanish iterbio (ytterbium), Italian afnio (hafnium), Swedish moskovium (moscovium); but those modifications do not affect chemical symbols: "Yb", "Hf", "Mc".
Chemical symbols are understood internationally when element names might require translation. There have sometimes been differences in the past. For example, Germans in the past have used "J" (for the alternate name Jod) for iodine, but now use "I" and Iod.
The first letter of a chemical symbol is always capitalized, as in the preceding examples, and the subsequent letters, if any, are always lower case (small letters). Thus, the symbols for californium and einsteinium are Cf and Es.
General chemical symbols
There are also symbols in chemical equations for groups of chemical elements, for example in comparative formulas. These are often a single capital letter, and the letters are reserved and not used for names of specific elements. For example, an "X" indicates a variable group (usually a halogen) in a class of compounds, while "R" is a
At least two additional, two-letter generic chemical symbols are also in informal usage, "Ln" for any
Isotope symbols
Isotopes are distinguished by the atomic mass number (total protons and neutrons) for a particular isotope of an element, with this number combined with the pertinent element's symbol. IUPAC prefers that isotope symbols be written in superscript notation when practical, for example 12C and 235U. However, other notations, such as carbon-12 and uranium-235, or C-12 and U-235, are also used.
As a special case, the three naturally occurring isotopes of the element hydrogen are often specified as H for 1H (
Origin of the elements
This section needs additional citations for verification. (April 2021) |
Only about 4% of the total mass of the universe is made of atoms or ions, and thus represented by chemical elements. This fraction is about 15% of the total matter, with the remainder of the matter (85%) being dark matter. The nature of dark matter is unknown, but it is not composed of atoms of chemical elements because it contains no protons, neutrons, or electrons. (The remaining non-matter part of the mass of the universe is composed of the even less well understood dark energy).
The 94 naturally occurring chemical elements were produced by at least four classes of astrophysical process. Most of the hydrogen, helium and a very small quantity of lithium were produced in the first few minutes of the Big Bang. This Big Bang nucleosynthesis happened only once; the other processes are ongoing. Nuclear fusion inside stars produces elements through stellar nucleosynthesis, including all elements from carbon to iron in atomic number. Elements higher in atomic number than iron, including heavy elements like uranium and plutonium, are produced by various forms of explosive nucleosynthesis in supernovae and neutron star mergers. The light elements lithium, beryllium and boron are produced mostly through cosmic ray spallation (fragmentation induced by cosmic rays) of carbon, nitrogen, and oxygen.
During the early phases of the Big Bang, nucleosynthesis of hydrogen nuclei resulted in the production of hydrogen-1 (
On Earth (and elsewhere), trace amounts of various elements continue to be produced from other elements as products of nuclear transmutation processes. These include some produced by cosmic rays or other nuclear reactions (see cosmogenic and nucleogenic nuclides), and others produced as decay products of long-lived primordial nuclides.[25] For example, trace (but detectable) amounts of carbon-14 (14C) are continually produced in the atmosphere by cosmic rays impacting nitrogen atoms, and argon-40 (40Ar) is continually produced by the decay of primordially occurring but unstable potassium-40 (40K). Also, three primordially occurring but radioactive actinides, thorium, uranium, and plutonium, decay through a series of recurrently produced but unstable radioactive elements such as radium and radon, which are transiently present in any sample of these metals or their ores or compounds. Three other radioactive elements, technetium, promethium, and neptunium, occur only incidentally in natural materials, produced as individual atoms by nuclear fission of the nuclei of various heavy elements or in other rare nuclear processes.
In addition to the 94 naturally occurring elements, several
Abundance
The following graph (note log scale) shows the abundance of elements in our Solar System. The table shows the twelve most common elements in our galaxy (estimated spectroscopically), as measured in
The abundance of elements in the Solar System is in keeping with their origin from nucleosynthesis in the Big Bang and a number of progenitor supernova stars. Very abundant hydrogen and helium are products of the Big Bang, but the next three elements are rare since they had little time to form in the Big Bang and are not made in stars (they are, however, produced in small quantities by the breakup of heavier elements in interstellar dust, as a result of impact by cosmic rays). Beginning with carbon, elements are produced in stars by buildup from alpha particles (helium nuclei), resulting in an alternatingly larger abundance of elements with even atomic numbers (these are also more stable). In general, such elements up to iron are made in large stars in the process of becoming supernovas. Iron-56 is particularly common, since it is the most stable element that can easily be made from alpha particles (being a product of decay of radioactive nickel-56, ultimately made from 14 helium nuclei). Elements heavier than iron are made in energy-absorbing processes in large stars, and their abundance in the universe (and on Earth) generally decreases with their atomic number.
The abundance of the chemical elements on Earth varies from air to crust to ocean, and in various types of life. The abundance of elements in Earth's crust differs from that in the Solar System (as seen in the Sun and heavy planets like Jupiter) mainly in selective loss of the very lightest elements (hydrogen and helium) and also volatile neon, carbon (as hydrocarbons), nitrogen and sulfur, as a result of solar heating in the early formation of the solar system. Oxygen, the most abundant Earth element by mass, is retained on Earth by combination with silicon. Aluminium at 8% by mass is more common in the Earth's crust than in the universe and solar system, but the composition of the far more bulky mantle, which has magnesium and iron in place of aluminium (which occurs there only at 2% of mass) more closely mirrors the elemental composition of the solar system, save for the noted loss of volatile elements to space, and loss of iron which has migrated to the Earth's core.
The composition of the human body, by contrast, more closely follows the composition of seawater—save that the human body has additional stores of carbon and nitrogen necessary to form the proteins and nucleic acids, together with phosphorus in the nucleic acids and energy transfer molecule adenosine triphosphate (ATP) that occurs in the cells of all living organisms. Certain kinds of organisms require particular additional elements, for example the magnesium in chlorophyll in green plants, the calcium in mollusc shells, or the iron in the hemoglobin in vertebrate animals' red blood cells.
Elements in our galaxy | Parts per million by mass |
---|---|
Hydrogen | 739,000 |
Helium | 240,000 |
Oxygen | 10,400 |
Carbon | 4,600 |
Neon | 1,340 |
Iron | 1,090 |
Nitrogen | 960 |
Silicon | 650 |
Magnesium | 580 |
Sulfur | 440 |
Potassium | 210 |
Nickel | 100 |
Essential elements[27][28][29][30][31] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
H | He | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Li | Be | B | C | N | O | F | Ne | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Na | Mg | Al | Si | P | S | Cl | Ar | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
K | Ca | Sc | Ti | V | Cr | Mn | Fe | Co | Ni | Cu | Zn | Ga | Ge | As | Se | Br | Kr | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Rb | Sr | Y | Zr | Nb | Mo | Tc | Ru | Rh | Pd | Ag | Cd | In | Sn | Sb | Te | I | Xe | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Cs | Ba | * | Lu | Hf | Ta | W | Re | Os | Ir | Pt | Au | Hg | Tl | Pb | Bi | Po | At | Rn | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Fr | Ra | ** | Lr | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn | Nh | Fl | Mc | Lv | Ts | Og | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
* | La | Ce | Pr | Nd | Pm | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm | Yb | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
** | Ac | Th | Pa | U | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No |
Legend:
The four basic organic elements
Quantity elements
Essential trace elements
Essentiality or function in mammals debated
No evidence for biological action in mammals, but essential in some lower organisms.
(In the case of the lanthanides, the definition of an essential nutrient as being indispensable and irreplaceable is not completely applicable due to their extreme similarity. The stable early lanthanides La–Nd are known to stimulate the growth of various lanthanide-using organisms, and Sm–Gd show lesser effects for some such organisms. The later elements in the lanthanide series do not appear to have such effects.)[32] |
History
Evolving definitions
The concept of an "element" as an indivisible substance has developed through three major historical phases: Classical definitions (such as those of the ancient Greeks), chemical definitions, and atomic definitions.
Classical definitions
Ancient philosophy posited a set of classical elements to explain observed patterns in nature. These elements originally referred to earth, water, air and fire rather than the chemical elements of modern science.
The term 'elements' (stoicheia) was first used by the Greek philosopher
Aristotle, c. 350 BCE, also used the term stoicheia and added a fifth element called aether, which formed the heavens. Aristotle defined an element as:
Element – one of those bodies into which other bodies can decompose, and that itself is not capable of being divided into other.[35]
Chemical definitions
Robert Boyle
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In 1661, in The Sceptical Chymist, Robert Boyle proposed his theory of corpuscularism which favoured the analysis of matter as constituted by irreducible units of matter (atoms) and, choosing to side with neither Aristotle's view of the four elements nor Paracelsus' view of three fundamental elements, left open the question of the number of elements. Boyle argued against a pre-determined number of elements—directly against Paracelsus' three principles (sulfur, mercury, and salt), indirectly against the "Aristotelian" elements (earth, water, air, and fire), for Boyle felt that the arguments against the former were at least as valid against the latter.
Much of what I am to deliver ... may be indifferently apply'd to the four Peripatetick Elements, and the three Chymical Principles ... the Chymical Hypothesis seeming to be much more countenanc'd by Experience then the other, it will be expedient to insist chiefly upon the disproving of that; especially since most of the Arguments that are imploy'd against it, may, by a little variation, be made ... at least as strongly against the less plausible, Aristotelian Doctrine.[36]
Then Boyle stated his own view in four propositions. In the first and second, he suggests that matter consists of particles, but that these particles may be difficult to separate. Boyle used the concept of "corpuscles"—or "atomes",[37] as he also called them—to explain how a limited number of elements could combine into a vast number of compounds.
Propos. I. ... At the first Production of mixt Bodies, the Universal Matter whereof they ... consisted, was actually divided into little Particles.[38] ... The Generation ... and wasting of Bodies ... and ... the Chymical Resolutions of mixt Bodies, and ... Operations of ... Fires upon them ... manifest their consisting of parts very minute... Epicurus ... as you well know, supposes ... all ... Bodies ... to be produc'd by ... Atomes, moving themselves to and fro ... in the ... Infinite Vacuum.[39] ... Propos. II. ... These minute Particles ... were ... associated into minute ... Clusters ... not easily dissipable into such Particles as compos'd them.[40] ... If we assigne to the Corpuscles, whereof each Element consists, a peculiar size and shape ... such ... Corpuscles may be mingled in such various Proportions, and ... connected so many ... wayes, that an almost incredible number of ... Concretes may be compos'd of them.[41]
Boyle explained that gold reacts with aqua regia, and mercury with nitric acid, sulfuric acid, and sulfur to produce various "compounds", and that they could be recovered from those compounds, just as would be expected of elements. Yet, Boyle did not consider gold,[42] mercury,[43] or lead[42] elements, but rather—together with wine[44]—"perfectly mixt bodies".
Quicksilver ... with Aqua fortis will be brought into a ... white Powder ... with Sulphur it will compose a blood-red ... Cinaber. And yet out of all these exotick Compounds, we may recover the very same running Mercury.[45] ... Propos. III. ... From most of such mixt Bodies ... there may by the Help of the Fire, be actually obtain'd a determinate number (whether Three, Four or Five, or fewer or more) of Substances ... The Chymists are wont to call the Ingredients of mixt Bodies, Principles, as the Aristotelians name them Elements. ... Principles ... as not being compounded of any more primary Bodies: and Elements, in regard that all mix'd Bodies are compounded of them.[46]
Even though Boyle is largely regarded as the first modern chemist, The Sceptical Chymist still contains old ideas about the elements, alien to a modern viewpoint. Sulphur, for example, is not only the familiar yellow non-metal, but also an inflammable "spirit".[44]
Isaac Watts
In 1724, in his book Logick, the English minister and logician Isaac Watts enumerated the elements then recognized by chemists. Watts' list of elements included two of Paracelsus' principles (sulfur and salt) and two classical elements (earth and water) as well as "spirit". Watts did, however, note a lack of consensus among chemists.[47]
Elements are such Substances as cannot be resolved, or reduced, into two or more Substances of different Kinds. ... Followers of Aristotle made Fire, Air, Earth and Water to be the four Elements, of which all earthly Things were compounded; and they suppos'd the Heavens to be a Quintessence, or fifth sort of Body, distinct from all these : But, since experimental Philosophy ... have been better understood, this Doctrine has been abundantly refuted. The Chymists make Spirit, Salt, Sulphur, Water and Earth to be their five Elements, because they can reduce all terrestrial Things to these five :.. tho' they are not all agreed.
Antoine Lavoisier, Jöns Jakob Berzelius, and Dmitri Mendeleev
From Boyle until the early 20th century, an element was defined as a pure substance that could not be decomposed into any simpler substance. Put another way, a chemical element cannot be transformed into other chemical elements by chemical processes. Elements during this time were generally distinguished by their atomic weights, a property measurable with fair accuracy by available analytical techniques.
Atomic definitions
The 1913 discovery by English physicist
By 1914, eighty-seven elements were known, all naturally occurring (see
Discovery and recognition of various elements
Ten materials familiar to various prehistoric cultures are now known to be chemical elements: Carbon, copper, gold, iron, lead, mercury, silver, sulfur, tin, and zinc. Three additional materials now accepted as elements, arsenic, antimony, and bismuth, were recognized as distinct substances prior to 1500 AD. Phosphorus, cobalt, and platinum were isolated before 1750.
Most of the remaining naturally occurring chemical elements were identified and characterized by 1900, including:
- Such now-familiar , magnesium, and tungsten
- Reactive metals such as lithium, sodium, potassium, and calcium
- The halogens fluorine, chlorine, bromine, and iodine
- Gases such as hydrogen, oxygen, nitrogen, helium, argon, and neon
- Most of the .
- The more common radioactive elements, including uranium, thorium, radium, and radon
Elements isolated or produced since 1900 include:
- The three remaining undiscovered regularly occurring stable natural elements: hafnium, lutetium, and rhenium
- Plutonium, which was first produced synthetically in 1940 by Glenn T. Seaborg, but is now also known from a few long-persisting natural occurrences
- The three incidentally occurring natural elements (neptunium, promethium, and technetium), which were all first produced synthetically but later discovered in trace amounts in certain geological samples
- Four scarce decay products of uranium or thorium (astatine, francium, actinium, and protactinium), and
- Various synthetic
Recently discovered elements
The first transuranium element (element with atomic number greater than 92) discovered was neptunium in 1940. Since 1999, claims for the discovery of new elements have been considered by the IUPAC/IUPAP Joint Working Party. As of January 2016, all 118 elements have been confirmed by IUPAC as being discovered. The discovery of element 112 was acknowledged in 2009, and the name copernicium and the atomic symbol Cn were suggested for it.[50] The name and symbol were officially endorsed by IUPAC on 19 February 2010.[51] The heaviest element that is believed to have been synthesized to date is element 118, oganesson, on 9 October 2006, by the Flerov Laboratory of Nuclear Reactions in Dubna, Russia.[10][52] Tennessine, element 117 was the latest element claimed to be discovered, in 2009.[53] On 28 November 2016, scientists at the IUPAC officially recognized the names for the four newest chemical elements, with atomic numbers 113, 115, 117, and 118.[54][55]
List of the 118 known chemical elements
The following sortable table shows the 118 known chemical elements.
- Atomic number, Element, and Symbol all serve independently as unique identifiers.
- Element names are those accepted by IUPAC.
- Block indicates the periodic table block for each element: red = s-block, yellow = p-block, blue = d-block, green = f-block.
- Group and period refer to an element's position in the periodic table. Group numbers here show the currently accepted numbering; for older numberings, see Group (periodic table).
Element | Origin of name[56][57] | Group | Period | Block | Standard atomic weight Ar°(E)[a] |
Density[b][c] | Melting point[d] | Boiling point[e] | Specific heat capacity[f] |
Electronegativity[g] | Abundance in Earth's crust[h] |
Origin[i] | Phase at r.t.[j] | ||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Atomic number Z |
Symbol | Name | (Da) | (g/cm3) | (K) | (K) | (J/g · K) | (mg/kg) | |||||||
1 | H | Hydrogen | Greek elements hydro- and -gen, 'water-forming' | 1 | 1 | s-block | 1.0080 | 0.00008988 | 14.01 | 20.28 | 14.304 | 2.20 | 1400 | primordial | gas |
2 | He | Helium | Greek hḗlios, 'sun' | 18 | 1 | s-block | 4.0026 | 0.0001785 | –[k] | 4.22 | 5.193 | – | 0.008 | primordial | gas |
3 | Li | Lithium | Greek líthos, ' stone '
|
1 | 2 | s-block | 6.94 | 0.534 | 453.69 | 1560 | 3.582 | 0.98 | 20 | primordial | solid |
4 | Be | Beryllium | Beryl, a mineral (ultimately from the name of Belur in southern India)[58] | 2 | 2 | s-block | 9.0122 | 1.85 | 1560 | 2742 | 1.825 | 1.57 | 2.8 | primordial | solid |
5 | B | Boron | Borax, a mineral (from Arabic bawraq, Middle Persian *bōrag) | 13 | 2 | p-block | 10.81 | 2.34 | 2349 | 4200 | 1.026 | 2.04 | 10 | primordial | solid |
6 | C | Carbon | Latin carbo, 'coal' | 14 | 2 | p-block | 12.011 | 2.267 | >4000 | 4300 | 0.709 | 2.55 | 200 | primordial | solid |
7 | N | Nitrogen | Greek nítron and -gen, 'niter-forming' | 15 | 2 | p-block | 14.007 | 0.0012506 | 63.15 | 77.36 | 1.04 | 3.04 | 19 | primordial | gas |
8 | O | Oxygen | Greek oxy- and -gen, 'acid-forming' | 16 | 2 | p-block | 15.999 | 0.001429 | 54.36 | 90.20 | 0.918 | 3.44 | 461000 | primordial | gas |
9 | F | Fluorine | Latin fluere, 'to flow' | 17 | 2 | p-block | 18.998 | 0.001696 | 53.53 | 85.03 | 0.824 | 3.98 | 585 | primordial | gas |
10 | Ne | Neon | Greek néon, 'new' | 18 | 2 | p-block | 20.180 | 0.0009002 | 24.56 | 27.07 | 1.03 | – | 0.005 | primordial | gas |
11 | Na | Sodium | Coined by ' | 1 | 3 | s-block | 22.990 | 0.968 | 370.87 | 1156 | 1.228 | 0.93 | 23600 | primordial | solid |
12 | Mg | Magnesium | Magnesia, a district of Eastern Thessaly in Greece | 2 | 3 | s-block | 24.305 | 1.738 | 923 | 1363 | 1.023 | 1.31 | 23300 | primordial | solid |
13 | Al | Aluminium | Alumina, from Latin alumen (gen. aluminis), 'bitter salt, alum' | 13 | 3 | p-block | 26.982 | 2.70 | 933.47 | 2792 | 0.897 | 1.61 | 82300 | primordial | solid |
14 | Si | Silicon | Latin silex, 'flint' (originally silicium) | 14 | 3 | p-block | 28.085 | 2.3290 | 1687 | 3538 | 0.705 | 1.9 | 282000 | primordial | solid |
15 | P | Phosphorus | Greek phōsphóros, 'light-bearing' | 15 | 3 | p-block | 30.974 | 1.823 | 317.30 | 550 | 0.769 | 2.19 | 1050 | primordial | solid |
16 | S | Sulfur | Latin | 16 | 3 | p-block | 32.06 | 2.07 | 388.36 | 717.87 | 0.71 | 2.58 | 350 | primordial | solid |
17 | Cl | Chlorine | Greek chlōrós, 'greenish yellow' | 17 | 3 | p-block | 35.45 | 0.0032 | 171.6 | 239.11 | 0.479 | 3.16 | 145 | primordial | gas |
18 | Ar | Argon | Greek argós, 'idle' (because of its inertness) | 18 | 3 | p-block | 39.95 | 0.001784 | 83.80 | 87.30 | 0.52 | – | 3.5 | primordial | gas |
19 | K | Potassium | Neo-Latin potassa, 'potash', itself from pot and ash · Symbol K is derived from Neo-Latin kalium, from German |
1 | 4 | s-block | 39.098 | 0.89 | 336.53 | 1032 | 0.757 | 0.82 | 20900 | primordial | solid |
20 | Ca | Calcium | Latin calx, 'lime' | 2 | 4 | s-block | 40.078 | 1.55 | 1115 | 1757 | 0.647 | 1.00 | 41500 | primordial | solid |
21 | Sc | Scandium | Latin Scandia, 'Scandinavia' | 3 | 4 | d-block | 44.956 | 2.985 | 1814 | 3109 | 0.568 | 1.36 | 22 | primordial | solid |
22 | Ti | Titanium | Titans , the sons of the earth goddess of Greek mythology
|
4 | 4 | d-block | 47.867 | 4.506 | 1941 | 3560 | 0.523 | 1.54 | 5650 | primordial | solid |
23 | V | Vanadium | 5 | 4 | d-block | 50.942 | 6.11 | 2183 | 3680 | 0.489 | 1.63 | 120 | primordial | solid | |
24 | Cr | Chromium | Greek chróma, ' colour '
|
6 | 4 | d-block | 51.996 | 7.15 | 2180 | 2944 | 0.449 | 1.66 | 102 | primordial | solid |
25 | Mn | Manganese | Corrupted from magnesia negra; see § magnesium | 7 | 4 | d-block | 54.938 | 7.21 | 1519 | 2334 | 0.479 | 1.55 | 950 | primordial | solid |
26 | Fe | Iron | English, from Proto-Celtic *īsarnom ('iron'), from a root meaning 'blood'
· Symbol Fe is derived from Latin ferrum |
8 | 4 | d-block | 55.845 | 7.874 | 1811 | 3134 | 0.449 | 1.83 | 56300 | primordial | solid |
27 | Co | Cobalt | German Kobold, 'goblin' | 9 | 4 | d-block | 58.933 | 8.90 | 1768 | 3200 | 0.421 | 1.88 | 25 | primordial | solid |
28 | Ni | Nickel | Nickel, a mischievous sprite of German miner mythology | 10 | 4 | d-block | 58.693 | 8.908 | 1728 | 3186 | 0.444 | 1.91 | 84 | primordial | solid |
29 | Cu | Copper | English, from Latin cuprum, from Ancient Greek Kýpros 'Cyprus' | 11 | 4 | d-block | 63.546 | 8.96 | 1357.77 | 2835 | 0.385 | 1.90 | 60 | primordial | solid |
30 | Zn | Zinc | Most likely from German Zinke, 'prong' or 'tooth', though some suggest Persian sang, 'stone' | 12 | 4 | d-block | 65.38 | 7.14 | 692.88 | 1180 | 0.388 | 1.65 | 70 | primordial | solid |
31 | Ga | Gallium | Latin Gallia, 'France '
|
13 | 4 | p-block | 69.723 | 5.91 | 302.9146 | 2673 | 0.371 | 1.81 | 19 | primordial | solid |
32 | Ge | Germanium | Latin Germania, 'Germany' | 14 | 4 | p-block | 72.630 | 5.323 | 1211.40 | 3106 | 0.32 | 2.01 | 1.5 | primordial | solid |
33 | As | Arsenic | Middle English, from Old Iranian *zarniya-ka, 'golden'
|
15 | 4 | p-block | 74.922 | 5.727 | 1090[l] | 887 | 0.329 | 2.18 | 1.8 | primordial | solid |
34 | Se | Selenium | Greek selḗnē, 'moon' | 16 | 4 | p-block | 78.971 | 4.81 | 453 | 958 | 0.321 | 2.55 | 0.05 | primordial | solid |
35 | Br | Bromine | Greek brômos, 'stench' | 17 | 4 | p-block | 79.904 | 3.1028 | 265.8 | 332.0 | 0.474 | 2.96 | 2.4 | primordial | liquid |
36 | Kr | Krypton | Greek kryptós, 'hidden' | 18 | 4 | p-block | 83.798 | 0.003749 | 115.79 | 119.93 | 0.248 | 3.00 | 1×10−4 | primordial | gas |
37 | Rb | Rubidium | Latin rubidus, 'deep red' | 1 | 5 | s-block | 85.468 | 1.532 | 312.46 | 961 | 0.363 | 0.82 | 90 | primordial | solid |
38 | Sr | Strontium | Strontian, a village in Scotland, where it was found | 2 | 5 | s-block | 87.62 | 2.64 | 1050 | 1655 | 0.301 | 0.95 | 370 | primordial | solid |
39 | Y | Yttrium | Ytterby, Sweden, where it was found; see also terbium, erbium, ytterbium | 3 | 5 | d-block | 88.906 | 4.472 | 1799 | 3609 | 0.298 | 1.22 | 33 | primordial | solid |
40 | Zr | Zirconium | Zircon, a mineral, from Persian zargun, 'gold-hued' | 4 | 5 | d-block | 91.224 | 6.52 | 2128 | 4682 | 0.278 | 1.33 | 165 | primordial | solid |
41 | Nb | Niobium | Niobe, daughter of king Tantalus from Greek mythology; see also tantalum | 5 | 5 | d-block | 92.906 | 8.57 | 2750 | 5017 | 0.265 | 1.6 | 20 | primordial | solid |
42 | Mo | Molybdenum | Greek molýbdaina, 'piece of lead', from mólybdos, 'lead', due to confusion with lead ore galena (PbS) | 6 | 5 | d-block | 95.95 | 10.28 | 2896 | 4912 | 0.251 | 2.16 | 1.2 | primordial | solid |
43 | Tc | Technetium | Greek tekhnētós, 'artificial' | 7 | 5 | d-block | [97][a] | 11 | 2430 | 4538 | – | 1.9 | ~ 3×10−9 | from decay | solid |
44 | Ru | Ruthenium | Neo-Latin Ruthenia, 'Russia' | 8 | 5 | d-block | 101.07 | 12.45 | 2607 | 4423 | 0.238 | 2.2 | 0.001 | primordial | solid |
45 | Rh | Rhodium | Greek ' | 9 | 5 | d-block | 102.91 | 12.41 | 2237 | 3968 | 0.243 | 2.28 | 0.001 | primordial | solid |
46 | Pd | Palladium | Pallas, an asteroid, considered a planet at the time | 10 | 5 | d-block | 106.42 | 12.023 | 1828.05 | 3236 | 0.244 | 2.20 | 0.015 | primordial | solid |
47 | Ag | Silver | English, from a common Germanic root · Symbol Ag is derived from Latin argentum |
11 | 5 | d-block | 107.87 | 10.49 | 1234.93 | 2435 | 0.235 | 1.93 | 0.075 | primordial | solid |
48 | Cd | Cadmium | Neo-Latin Kadmos , legendary founder of Thebes
|
12 | 5 | d-block | 112.41 | 8.65 | 594.22 | 1040 | 0.232 | 1.69 | 0.159 | primordial | solid |
49 | In | Indium | Latin indicum, 'indigo', the blue colour found in its spectrum | 13 | 5 | p-block | 114.82 | 7.31 | 429.75 | 2345 | 0.233 | 1.78 | 0.25 | primordial | solid |
50 | Sn | Tin | English, from a common Germanic root · Symbol Sn is derived from Latin stannum |
14 | 5 | p-block | 118.71 | 7.265 | 505.08 | 2875 | 0.228 | 1.96 | 2.3 | primordial | solid |
51 | Sb | Antimony | Latin antimonium, the origin of which is uncertain: folk etymologies suggest it is derived from Greek antí ('against') + mónos ('alone'), or Old French anti-moine, 'Monk's bane', but it could plausibly be from or related to Arabic ʾiṯmid, 'antimony', reformatted as a Latin word · Symbol Sb is derived from Latin stibium 'stibnite' |
15 | 5 | p-block | 121.76 | 6.697 | 903.78 | 1860 | 0.207 | 2.05 | 0.2 | primordial | solid |
52 | Te | Tellurium | Latin tellus, 'the ground, earth' | 16 | 5 | p-block | 127.60 | 6.24 | 722.66 | 1261 | 0.202 | 2.1 | 0.001 | primordial | solid |
53 | I | Iodine | French iode, from Greek ioeidḗs, 'violet' | 17 | 5 | p-block | 126.90 | 4.933 | 386.85 | 457.4 | 0.214 | 2.66 | 0.45 | primordial | solid |
54 | Xe | Xenon | Greek xénon, neuter form of xénos 'strange, foreign' | 18 | 5 | p-block | 131.29 | 0.005894 | 161.4 | 165.03 | 0.158 | 2.60 | 3×10−5 | primordial | gas |
55 | Cs | Caesium | Latin caesius, 'sky-blue' | 1 | 6 | s-block | 132.91 | 1.93 | 301.59 | 944 | 0.242 | 0.79 | 3 | primordial | solid |
56 | Ba | Barium | Greek barýs, 'heavy' | 2 | 6 | s-block | 137.33 | 3.51 | 1000 | 2170 | 0.204 | 0.89 | 425 | primordial | solid |
57 | La | Lanthanum | Greek lanthánein, 'to lie hidden' | f-block groups | 6 | f-block | 138.91 | 6.162 | 1193 | 3737 | 0.195 | 1.1 | 39 | primordial | solid |
58 | Ce | Cerium | Ceres, a dwarf planet, considered a planet at the time | f-block groups | 6 | f-block | 140.12 | 6.770 | 1068 | 3716 | 0.192 | 1.12 | 66.5 | primordial | solid |
59 | Pr | Praseodymium | Greek prásios dídymos, 'green twin' | f-block groups | 6 | f-block | 140.91 | 6.77 | 1208 | 3793 | 0.193 | 1.13 | 9.2 | primordial | solid |
60 | Nd | Neodymium | Greek néos dídymos, 'new twin' | f-block groups | 6 | f-block | 144.24 | 7.01 | 1297 | 3347 | 0.19 | 1.14 | 41.5 | primordial | solid |
61 | Pm | Promethium | Prometheus, a figure in Greek mythology | f-block groups | 6 | f-block | [145] | 7.26 | 1315 | 3273 | – | 1.13 | 2×10−19 | from decay | solid |
62 | Sm | Samarium | V. Samarsky-Bykhovets , Russian mine official
|
f-block groups | 6 | f-block | 150.36 | 7.52 | 1345 | 2067 | 0.197 | 1.17 | 7.05 | primordial | solid |
63 | Eu | Europium | Europe | f-block groups | 6 | f-block | 151.96 | 5.244 | 1099 | 1802 | 0.182 | 1.2 | 2 | primordial | solid |
64 | Gd | Gadolinium | Gadolinite, a mineral named after Johan Gadolin, Finnish chemist, physicist and mineralogist | f-block groups | 6 | f-block | 157.25 | 7.90 | 1585 | 3546 | 0.236 | 1.2 | 6.2 | primordial | solid |
65 | Tb | Terbium | Ytterby, Sweden, where it was found; see also yttrium, erbium, ytterbium | f-block groups | 6 | f-block | 158.93 | 8.23 | 1629 | 3503 | 0.182 | 1.2 | 1.2 | primordial | solid |
66 | Dy | Dysprosium | Greek dysprósitos, 'hard to get' | f-block groups | 6 | f-block | 162.50 | 8.540 | 1680 | 2840 | 0.17 | 1.22 | 5.2 | primordial | solid |
67 | Ho | Holmium | Neo-Latin Holmia, 'Stockholm' | f-block groups | 6 | f-block | 164.93 | 8.79 | 1734 | 2993 | 0.165 | 1.23 | 1.3 | primordial | solid |
68 | Er | Erbium | Ytterby, Sweden, where it was found; see also yttrium, terbium, ytterbium | f-block groups | 6 | f-block | 167.26 | 9.066 | 1802 | 3141 | 0.168 | 1.24 | 3.5 | primordial | solid |
69 | Tm | Thulium | Thule, the ancient name for an unclear northern location | f-block groups | 6 | f-block | 168.93 | 9.32 | 1818 | 2223 | 0.16 | 1.25 | 0.52 | primordial | solid |
70 | Yb | Ytterbium | Ytterby, Sweden, where it was found; see also yttrium, terbium, erbium | f-block groups | 6 | f-block | 173.05 | 6.90 | 1097 | 1469 | 0.155 | 1.1 | 3.2 | primordial | solid |
71 | Lu | Lutetium | Latin Lutetia', 'Paris' | 3 | 6 | d-block | 174.97 | 9.841 | 1925 | 3675 | 0.154 | 1.27 | 0.8 | primordial | solid |
72 | Hf | Hafnium | Neo-Latin Hafnia, 'Copenhagen' (from Danish havn, harbour) | 4 | 6 | d-block | 178.49 | 13.31 | 2506 | 4876 | 0.144 | 1.3 | 3 | primordial | solid |
73 | Ta | Tantalum | King Tantalus, father of Niobe from Greek mythology; see also niobium | 5 | 6 | d-block | 180.95 | 16.69 | 3290 | 5731 | 0.14 | 1.5 | 2 | primordial | solid |
74 | W | Tungsten | Swedish tung sten, 'heavy stone' · Symbol W is from Wolfram, originally from Middle High German wolf-rahm 'wolf's foam' describing the mineral wolframite[59] |
6 | 6 | d-block | 183.84 | 19.25 | 3695 | 5828 | 0.132 | 2.36 | 1.3 | primordial | solid |
75 | Re | Rhenium | Latin Rhenus, 'Rhine' | 7 | 6 | d-block | 186.21 | 21.02 | 3459 | 5869 | 0.137 | 1.9 | 7×10−4 | primordial | solid |
76 | Os | Osmium | Greek smell '
|
8 | 6 | d-block | 190.23 | 22.59 | 3306 | 5285 | 0.13 | 2.2 | 0.002 | primordial | solid |
77 | Ir | Iridium | Iris, the Greek goddess of the rainbow | 9 | 6 | d-block | 192.22 | 22.56 | 2719 | 4701 | 0.131 | 2.20 | 0.001 | primordial | solid |
78 | Pt | Platinum | Spanish platina, 'little silver', from plata 'silver' | 10 | 6 | d-block | 195.08 | 21.45 | 2041.4 | 4098 | 0.133 | 2.28 | 0.005 | primordial | solid |
79 | Au | Gold | English, from the same Proto-Indo-European root as 'yellow' · Symbol Au is derived from Latin aurum |
11 | 6 | d-block | 196.97 | 19.3 | 1337.33 | 3129 | 0.129 | 2.54 | 0.004 | primordial | solid |
80 | Hg | Mercury | Mercury, Roman god of commerce, communication, and luck, known for his speed and mobility · Symbol Hg is derived from its Latin name hydrargyrum, from Greek hydrárgyros, 'water-silver' |
12 | 6 | d-block | 200.59 | 13.534 | 234.43 | 629.88 | 0.14 | 2.00 | 0.085 | primordial | liquid |
81 | Tl | Thallium | Greek thallós, 'green shoot or twig' | 13 | 6 | p-block | 204.38 | 11.85 | 577 | 1746 | 0.129 | 1.62 | 0.85 | primordial | solid |
82 | Pb | Lead | English, from Proto-Celtic *ɸloudom, from a root meaning 'flow'
· Symbol Pb is derived from Latin plumbum |
14 | 6 | p-block | 207.2 | 11.34 | 600.61 | 2022 | 0.129 | 1.87 ( 2+ )2.33 (4+) |
14 | primordial | solid |
83 | Bi | Bismuth | German Wismut, via Latin and Arabic from Greek psimúthion, 'white lead' | 15 | 6 | p-block | 208.98 | 9.78 | 544.7 | 1837 | 0.122 | 2.02 | 0.009 | primordial | solid |
84 | Po | Polonium | Latin Polonia, 'Poland', home country of Marie Curie, who discovered it | 16 | 6 | p-block | [209][a] | 9.196 | 527 | 1235 | – | 2.0 | 2×10−10 | from decay | solid |
85 | At | Astatine | Greek ástatos, 'unstable', alluding to its lack of stable isotopes | 17 | 6 | p-block | [210] | (8.91–8.95) | 575 | 610 | – | 2.2 | 3×10−20 | from decay | unknown phase |
86 | Rn | Radon | 18 | 6 | p-block | [222] | 0.00973 | 202 | 211.3 | 0.094 | 2.2 | 4×10−13 | from decay | gas | |
87 | Fr | Francium | France, home country of discoverer Marguerite Perey | 1 | 7 | s-block | [223] | (2.48) | 281 | 890 | – | >0.79[60] | ~ 1×10−18 | from decay | unknown phase |
88 | Ra | Radium | Coined in French by discoverer Marie Curie, from Latin radius, 'ray' | 2 | 7 | s-block | [226] | 5.5 | 973 | 2010 | 0.094 | 0.9 | 9×10−7 | from decay | solid |
89 | Ac | Actinium | Greek aktís, 'ray' | f-block groups | 7 | f-block | [227] | 10 | 1323 | 3471 | 0.12 | 1.1 | 5.5×10−10 | from decay | solid |
90 | Th | Thorium | Thor, the Scandinavian god of thunder | f-block groups | 7 | f-block | 232.04 | 11.7 | 2115 | 5061 | 0.113 | 1.3 | 9.6 | primordial | solid |
91 | Pa | Protactinium | English prefix proto- (from Greek prôtos, 'first, before') + actinium, since actinium is produced through the radioactive decay of protactinium | f-block groups | 7 | f-block | 231.04 | 15.37 | 1841 | 4300 | – | 1.5 | 1.4×10−6 | from decay | solid |
92 | U | Uranium | Uranus, the seventh planet in the Solar System | f-block groups | 7 | f-block | 238.03 | 19.1 | 1405.3 | 4404 | 0.116 | 1.38 | 2.7 | primordial | solid |
93 | Np | Neptunium | Neptune, the eighth planet in the Solar System | f-block groups | 7 | f-block | [237] | 20.45 | 917 | 4273 | – | 1.36 | ≤ 3×10−12 | from decay | solid |
94 | Pu | Plutonium | Pluto, a dwarf planet in the Solar System, considered a planet at the time | f-block groups | 7 | f-block | [244] | 19.85 | 912.5 | 3501 | – | 1.28 | ≤ 3×10−11 | from decay | solid |
95 | Am | Americium | The Americas, where the element was first synthesised, by analogy with its homologue § europium
|
f-block groups | 7 | f-block | [243] | 12 | 1449 | 2880 | – | 1.13 | – | synthetic | solid |
96 | Cm | Curium | Pierre Curie and Marie Curie, French physicists and chemists | f-block groups | 7 | f-block | [247] | 13.51 | 1613 | 3383 | – | 1.28 | – | synthetic | solid |
97 | Bk | Berkelium | Berkeley, California, where the element was first synthesised | f-block groups | 7 | f-block | [247] | 14.78 | 1259 | 2900 | – | 1.3 | – | synthetic | solid |
98 | Cf | Californium | California, where the element was first synthesised in the LBNL laboratory | f-block groups | 7 | f-block | [251] | 15.1 | 1173 | (1743)[b] | – | 1.3 | – | synthetic | solid |
99 | Es | Einsteinium | Albert Einstein, German physicist | f-block groups | 7 | f-block | [252] | 8.84 | 1133 | (1269) | – | 1.3 | – | synthetic | solid |
100 | Fm | Fermium | Enrico Fermi, Italian physicist | f-block groups | 7 | f-block | [257] | (9.7)[b] | (1125)[61] (1800)[62] |
– | – | 1.3 | – | synthetic | unknown phase |
101 | Md | Mendelevium | Dmitri Mendeleev, Russian chemist who proposed the periodic table | f-block groups | 7 | f-block | [258] | (10.3) | (1100) | – | – | 1.3 | – | synthetic | unknown phase |
102 | No | Nobelium | Alfred Nobel, Swedish chemist and engineer | f-block groups | 7 | f-block | [259] | (9.9) | (1100) | – | – | 1.3 | – | synthetic | unknown phase |
103 | Lr | Lawrencium | Ernest Lawrence, American physicist | 3 | 7 | d-block | [266] | (14.4) | (1900) | – | – | 1.3 | – | synthetic | unknown phase |
104 | Rf | Rutherfordium | Ernest Rutherford, chemist and physicist from New Zealand | 4 | 7 | d-block | [267] | (17) | (2400) | (5800) | – | – | – | synthetic | unknown phase |
105 | Db | Dubnium | Dubna, Russia, where the element was discovered in the JINR laboratory | 5 | 7 | d-block | [268] | (21.6) | – | – | – | – | – | synthetic | unknown phase |
106 | Sg | Seaborgium | Glenn T. Seaborg, American chemist | 6 | 7 | d-block | [269] | (23–24) | – | – | – | – | – | synthetic | unknown phase |
107 | Bh | Bohrium | Niels Bohr, Danish physicist | 7 | 7 | d-block | [270] | (26–27) | – | – | – | – | – | synthetic | unknown phase |
108 | Hs | Hassium | Neo-Latin Hassia, 'Hesse', a state in Germany | 8 | 7 | d-block | [269] | (27–29) | – | – | – | – | – | synthetic | unknown phase |
109 | Mt | Meitnerium | Lise Meitner, Austrian physicist | 9 | 7 | d-block | [278] | (27–28) | – | – | – | – | – | synthetic | unknown phase |
110 | Ds | Darmstadtium | Darmstadt, Germany, where the element was first synthesised in the GSI laboratories | 10 | 7 | d-block | [281] | (26–27) | – | – | – | – | – | synthetic | unknown phase |
111 | Rg | Roentgenium | Wilhelm Conrad Röntgen , German physicist
|
11 | 7 | d-block | [282] | (22–24) | – | – | – | – | – | synthetic | unknown phase |
112 | Cn | Copernicium | Nicolaus Copernicus, Polish astronomer | 12 | 7 | d-block | [285] | (14.0) | (283±11) | (340±10)[b] | – | – | – | synthetic | unknown phase |
113 | Nh | Nihonium | Japanese Nihon, 'Japan', where the element was first synthesised in the Riken laboratories | 13 | 7 | p-block | [286] | (16) | (700) | (1400) | – | – | – | synthetic | unknown phase |
114 | Fl | Flerovium | Flerov Laboratory of Nuclear Reactions, part of JINR, where the element was synthesised; itself named after Georgy Flyorov, Russian physicist | 14 | 7 | p-block | [289] | (11.4±0.3) | (284±50)[b] | – | – | – | – | synthetic | unknown phase |
115 | Mc | Moscovium | Moscow, Russia, where the element was first synthesised in the JINR laboratories | 15 | 7 | p-block | [290] | (13.5) | (700) | (1400) | – | – | – | synthetic | unknown phase |
116 | Lv | Livermorium | Lawrence Livermore National Laboratory in Livermore, California | 16 | 7 | p-block | [293] | (12.9) | (700) | (1100) | – | – | – | synthetic | unknown phase |
117 | Ts | Tennessine | Tennessee, United States, where Oak Ridge National Laboratory is located | 17 | 7 | p-block | [294] | (7.1–7.3) | (700) | (883) | – | – | – | synthetic | unknown phase |
118 | Og | Oganesson | Yuri Oganessian, Russian physicist | 18 | 7 | p-block | [294] | (7) | (325±15) | (450±10) | – | – | – | synthetic | unknown phase |
- ^ a b c Standard atomic weight
- '1.0080': abridged value, uncertainty ignored here
- '[97]', [ ] notation: massnumber of most stable isotope
- ^ a b c d e Values in ( ) brackets are predictions
- ^ Density (sources)
- ^ Melting point in kelvin (K) (sources)
- ^ Boiling point in kelvin (K) (sources)
- ^ Heat capacity (sources)
- ^ Electronegativity by Pauling (source)
- ^ Abundance of elements in Earth's crust
- ^ Primordial (=Earth's origin), from decay, or synthetic
- ^ Phase at Standard state (25 °C [77 °F], 100 kPa)
- ^ Helium melting point: helium does not solidify at a pressure of 1 bar (0.99 atm). Helium can only solidify at pressures above 25 atmosphere.
- ^ Arsenic: element sublimes at one atmosphere of pressure.
See also
- Biological roles of the elements
- Chemical database
- Discovery of the chemical elements
- Element collecting
- Fictional element
- Goldschmidt classification
- Island of stability
- List of nuclides
- List of the elements' densities
- Mineral (nutrient)
- Periodic Systems of Small Molecules
- Prices of chemical elements
- Systematic element name
- Table of nuclides
- Timeline of chemical element discoveries
- Roles of chemical elements
References
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Bibliography
- Boyle, R. (1661). The Sceptical Chymist: or Chymico-Physical Doubts & Paradoxes, Touching the Spagyrist's Principles Commonly call'd Hypostatical; As they are wont to be Propos'd and Defended by the Generality of Alchymists. Whereunto is præmis'd Part of another Discourse relating to the same Subject. Printed by J. Cadwell for J. Crooke.
Further reading
- Ball, P. (2004). The Elements: A Very Short Introduction. ISBN 978-0-19-284099-8.
- Emsley, J. (2003). Nature's Building Blocks: An A–Z Guide to the Elements. Oxford University Press. ISBN 978-0-19-850340-8.
- Gray, T. (2009). The Elements: A Visual Exploration of Every Known Atom in the Universe. Black Dog & Leventhal Publishers Inc. ISBN 978-1-57912-814-2.
- Scerri, E.R. (2007). The Periodic Table, Its Story and Its Significance. Oxford University Press. ISBN 978-0-19-530573-9.
- Strathern, P. (2000). Mendeleyev's Dream: The Quest for the Elements. ISBN 978-0-241-14065-9.
- Kean, Sam (2011). The Disappearing Spoon: And Other True Tales of Madness, Love, and the History of the World from the Periodic Table of the Elements. Back Bay Books.
- A.D. McNaught; A. Wilkinson, eds. (1997). Compendium of Chemical Terminology (2nd ed.). Oxford: Blackwell Scientific Publications. ISBN 978-0-9678550-9-7. XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins
External links
- Videos for each element by the University of Nottingham
- "Chemical Elements", In Our Time, BBC Radio 4 discussion with Paul Strathern, Mary Archer and John Murrell (25 May 2000)