Carbon group
Carbon group (group 14) | |||||||||||
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↓ Period | |||||||||||
2 | Other nonmetal
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3 | Silicon (Si) 14 Metalloid | ||||||||||
4 | Germanium (Ge) 32 Metalloid | ||||||||||
5 | Other metal
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6 | Other metal
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7 | Other metal
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Legend
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The carbon group is a
In modern IUPAC notation, it is called group 14. In the field of semiconductor physics, it is still universally called group IV. The group is also known as the tetrels (from the Greek word tetra, which means four), stemming from the Roman numeral IV in the group names, or (not coincidentally) from the fact that these elements have four valence electrons (see below). They are also known as the crystallogens[1] or adamantogens.[2]
Characteristics
Chemical
Like other groups, the members of this family show patterns in electron configuration, especially in the outermost shells, resulting in trends in chemical behavior:
Z | Element | No. of electrons/shell |
---|---|---|
6 | Carbon | 2, 4 |
14 | Silicon | 2, 8, 4 |
32 | Germanium | 2, 8, 18, 4 |
50 | Tin | 2, 8, 18, 18, 4 |
82 | Lead | 2, 8, 18, 32, 18, 4 |
114 | Flerovium | 2, 8, 18, 32, 32, 18, 4 (predicted) |
Each of the elements in this group has 4 electrons in its outer shell. An isolated, neutral group 14 atom has the s2 p2 configuration in the ground state. These elements, especially carbon and silicon, have a strong propensity for covalent bonding, which usually brings the outer shell to eight electrons. Bonds in these elements often lead to hybridisation where distinct s and p characters of the orbitals are erased. For single bonds, a typical arrangement has four pairs of sp3 electrons, although other cases exist too, such as three sp2 pairs in graphene and graphite. Double bonds are characteristic for carbon (alkenes, CO2...); the same for π-systems in general. The tendency to lose electrons increases as the size of the atom increases, as it does with increasing atomic number. Carbon alone forms negative ions, in the form of carbide (C4−) ions. Silicon and germanium, both metalloids, each can form +4 ions.
Among main group (groups 1,2, 13–17) alkyl derivatives QRn, where n is the standard bonding number for Q (see lambda convention), the group 14 derivatives QR4 are notable in being electron-precise: they are neither electron-deficient (having fewer electrons than an octet and tending to be Lewis acidic at Q and usually existing as oligomeric clusters or adducts with Lewis bases) nor electron-excessive (having lone pair(s) at Q and tending to be Lewis basic at Q). As a result, the group 14 alkyls have low chemical reactivity relative to the alkyl derivatives of other groups. In the case of carbon, the high bond dissociation energy of the C–C bond and lack of electronegativity difference between the central atom and the alkyl ligands render the saturated alkyl derivatives, the alkanes, particularly inert.[3]
Carbon forms tetrahalides with all the
Silicon forms several hydrides; two of them are SiH4 and Si2H6. Silicon forms tetrahalides with fluorine, chlorine, bromine, and iodine. Silicon also forms a dioxide and a disulfide.[5] Silicon nitride has the formula Si3N4.[6]
Germanium forms five hydrides. The first two germanium hydrides are GeH4 and Ge2H6. Germanium forms tetrahalides with all halogens except astatine and forms dihalides with all halogens except bromine and astatine. Germanium bonds to all natural single chalcogens except polonium, and forms dioxides, disulfides, and diselenides. Germanium nitride has the formula Ge3N4.[7]
Tin forms two hydrides: SnH4 and Sn2H6. Tin forms dihalides and tetrahalides with all halogens except astatine. Tin forms chalcogenides with one of each naturally occurring chalcogen except polonium, and forms chalcogenides with two of each naturally occurring chalcogen except polonium and tellurium.[8]
Lead forms one hydride, which has the formula PbH4. Lead forms dihalides and tetrahalides with fluorine and chlorine, and forms a dibromide and diiodide, although the tetrabromide and tetraiodide of lead are unstable. Lead forms four oxides, a sulfide, a selenide, and a telluride.[9]
There are no known compounds of flerovium.[10]
Physical
The boiling points of the carbon group tend to get lower with the heavier elements. Carbon, the lightest carbon group element, sublimes at 3825 °C. Silicon's boiling point is 3265 °C, germanium's is 2833 °C, tin's is 2602 °C, and lead's is 1749 °C. Flerovium is predicted boil in -60 °C.[11][12] The melting points of the carbon group elements have roughly the same trend as their boiling points. Silicon melts at 1414 °C, germanium melts at 939 °C, tin melts at 232 °C, and lead melts at 328 °C.[13]
Carbon's crystal structure is
The
The
Allotropes
Carbon has multiple
Silicon has two known allotropes that exist at room temperature. These allotropes are known as the amorphous and the crystalline allotropes. The amorphous allotrope is a brown powder. The crystalline allotrope is gray and has a metallic luster.[16]
Tin has two allotropes: α-tin, also known as gray tin, and β-tin. Tin is typically found in the β-tin form, a silvery metal. However, at standard pressure, β-tin converts to α-tin, a gray powder, at temperatures below 13.2 °C (55.8 °F). This can cause tin objects in cold temperatures to crumble to gray powder in a process known as tin pest or tin rot.[6][17]
Nuclear
At least two of the carbon group elements (tin and lead) have
Isotopes
There are 15 known
23
32 isotopes of germanium have been discovered. Five of these are naturally occurring. The most common is the stable isotope germanium-74, followed by the stable isotope germanium-72, the stable isotope germanium-70, and the stable isotope germanium-73. The isotope germanium-76 is a primordial radioisotope.[18]
40 isotopes of tin have been discovered. 14 of these occur in nature. The most common is tin-120, followed by tin-118, tin-116, tin-119, tin-117, tin-124, tin-122, tin-112, and tin-114: all of these are stable. Tin also has four radioisotopes that occur as the result of the radioactive decay of uranium. These isotopes are tin-121, tin-123, tin-125, and tin-126.[18]
38 isotopes of lead have been discovered. 9 of these are naturally occurring. The most common isotope is lead-208, followed by lead-206, lead-207, and lead-204: all of these are stable. 5 isotopes of lead occur from the radioactive decay of uranium and thorium. These isotopes are lead-209, lead-210, lead-211, lead-212 and lead-214.[18]
6 isotopes of flerovium (flerovium-284, flerovium-285, flerovium-286, flerovium-287, flerovium-288, and flerovium-289) have been discovered. None of these are naturally occurring. Flerovium's most stable isotope is flerovium-289, which has a half-life of 2.6 seconds.[18]
Occurrence
Carbon accumulates as the result of
Silicon is present in the Earth's crust at concentrations of 28%, making it the second most abundant element there. Silicon's concentration in seawater can vary from 30 parts per billion on the surface of the ocean to 2000 parts per billion deeper down. Silicon dust occurs in trace amounts in Earth's atmosphere.
Germanium makes up 2 parts per million of the Earth's crust, making it the 52nd most abundant element there. On average, germanium makes up 1 part per million of soil. Germanium makes up 0.5 parts per trillion of seawater. Organogermanium compounds are also found in seawater. Germanium occurs in the human body at concentrations of 71.4 parts per billion. Germanium has been found to exist in some very faraway stars.[18]
Tin makes up 2 parts per million of the Earth's crust, making it the 49th most abundant element there. On average, tin makes up 1 part per million of soil. Tin exists in seawater at concentrations of 4 parts per trillion. Tin makes up 428 parts per billion of the human body. Tin(IV) oxide occurs at concentrations of 0.1 to 300 parts per million in soils.[18] Tin also occurs in concentrations of one part per thousand in igneous rocks.[19]
Lead makes up 14 parts per million of the Earth's crust, making it the 36th most abundant element there. On average, lead makes up 23 parts per million of soil, but the concentration can reach 20000 parts per million (2 percent) near old lead mines. Lead exists in seawater at concentrations of 2 parts per trillion. Lead makes up 1.7 parts per million of the human body by weight. Human activity releases more lead into the environment than any other metal.[18]
Flerovium doesn't occur in nature at all, so it only exists in
History
Discoveries and uses in antiquity
Carbon, tin, and lead are a few of the elements well known in the ancient world, together with sulfur, iron, copper, mercury, silver, and gold.[20]
Silicon as silica in the form of rock crystal was familiar to the predynastic Egyptians, who used it for beads and small vases; to the early Chinese; and probably to many others of the ancients. The manufacture of glass containing silica was carried out both by the Egyptians – at least as early as 1500 BCE – and by the
The origins of tin seem to be lost in history. It appears that bronzes, which are alloys of copper and tin, were used by prehistoric man some time before the pure metal was isolated. Bronzes were common in early Mesopotamia, the Indus Valley, Egypt, Crete, Israel, and Peru. Much of the tin used by the early Mediterranean peoples apparently came from the
Lead is mentioned often in early Biblical accounts. The
Modern discoveries
Amorphous elemental silicon was first obtained pure in 1824 by the Swedish chemist Jöns Jacob Berzelius; impure silicon had already been obtained in 1811. Crystalline elemental silicon was not prepared until 1854, when it was obtained as a product of electrolysis.
Germanium is one of three elements the existence of which was predicted in 1869 by the Russian chemist Dmitri Mendeleev when he first devised his periodic table. However, the element was not actually discovered for some time. In September 1885, a miner discovered a mineral sample in a silver mine and gave it to the mine manager, who determined that it was a new mineral and sent the mineral to Clemens A. Winkler. Winkler realized that the sample was 75% silver, 18% sulfur, and 7% of an undiscovered element. After several months, Winkler isolated the element and determined that it was element 32.[18]
The first attempt to discover flerovium (then referred to as "element 114") was in 1969, at the Joint Institute for Nuclear Research, but it was unsuccessful. In 1977, researchers at the Joint Institute for Nuclear Research bombarded plutonium-244 atoms with calcium-48, but were again unsuccessful. This nuclear reaction was repeated in 1998, this time successfully.[18]
Etymologies
- Carbon comes from the Latin word carbo, meaning "charcoal".
- Silicon comes from the Latin word silex (or silicis), meaning "flint".
- Germanium comes from the Latin word Germania, the Latin name for Germany, which is the country where germanium was discovered.
- Stannum comes from the Latin word stannum, meaning "tin", from or related to Celtic staen.
- - The common name for stannum in English is tin, inherited directly from Old English. Possibly of common origin with stannum and staen.
- Plumbum comes from the Latin word plumbum meaning lead.
- - The common name for plumbum in English is lead, inherited directly from Old English. [18]
- - The common name for plumbum in English is lead, inherited directly from Old English. [18]
- Flerovium was named after Georgy Flyorov and his Institute.
Applications
Carbon is most commonly used in its
Germanium was used in semiconductors until the 1950s, when it was replaced by silicon.
80% of all lead produced goes into
Production
Carbon's allotrope diamond is produced mostly by
Silicon can be produced by heating silica with carbon.[22]
There are some germanium ores, such as
Mines output 300,000 metric tons of tin each year. China, Indonesia, Peru, Bolivia, and Brazil are the main producers of tin. The method by which tin is produced is to heat the tin mineral cassiterite (SnO2) with coke.[18]
The most commonly mined lead ore is
Biological role
Carbon is a key element to all known life. It is in all organic compounds, for example, DNA, steroids, and proteins.[6] Carbon's importance to life is primarily due to its ability to form numerous bonds with other elements.[17] There are 16 kilograms of carbon in a typical 70-kilogram human.[18]
A biological role for germanium is not known, although it does stimulate
Tin has been shown to be essential for proper growth in rats, but there is, as of 2013, no evidence to indicate that humans need tin in their diet. Plants do not require tin. However, plants do collect tin in their
Lead has no known biological role, and is in fact highly
Flerovium has no biological role and instead is found and made only in particle accelerators.
Toxicity
Elemental carbon is not generally toxic, but many of its compounds are, such as carbon monoxide and hydrogen cyanide. However, carbon dust can be dangerous because it lodges in the lungs in a manner similar to asbestos.[18]
Silicon minerals are not typically poisonous. However, silicon dioxide dust, such as that emitted by
Germanium can interfere with such
Some tin compounds are toxic to
Lead and its compounds, such as
Flerovium is too radioactive to test if its toxic or not although its high radioactivity alone would be toxic.
References
- . Retrieved 17 August 2019.
- ^ W. B. Jensen, The Periodic Law and Table Archived 2020-11-10 at the Wayback Machine.
- ISBN 978-0-471-66256-3.
- ^ Carbon compounds, retrieved January 24, 2013
- ^ Silicon compounds, retrieved January 24, 2013
- ^ a b c d e Gray, Theodore (2011), The Elements
- ^ Germanium compounds, retrieved January 24, 2013
- ^ Tin compounds, retrieved January 24, 2013
- ^ Lead compounds, retrieved January 24, 2013
- ^ Flerovium compounds, retrieved January 24, 2013
- ^ Archived at Ghostarchive and the Wayback Machine: Oganessian, Yu. Ts. (27 January 2017). "Discovering Superheavy Elements". Oak Ridge National Laboratory. Retrieved 21 April 2017.
- ^ Seaborg, G. T. "Transuranium element". Encyclopædia Britannica. Retrieved 2010-03-16.
- ^ a b c d e Jackson, Mark (2001), Periodic Table Advanced
- ^ Graphene, retrieved 20 January 2013
- ^ Carbon:Allotropes, archived from the original on 2013-01-17, retrieved 20 January 2013
- ^ Gagnon, Steve, The Element Silicon, retrieved January 20, 2013
- ^ a b c d e f g h Kean, Sam (2011), The Disappearing Spoon
- ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad Emsley, John (2011), Nature's Building Blocks
- ^ tin (Sn), Encyclopædia Britannica, 2013, retrieved February 24, 2013
- ^ Chemical Elements, retrieved 20 January 2013
- ^ Online Encyclopædia Britannica, Tin
- ^ ISBN 0-809-49663-1
- ^ Blum, Deborah (2010), The Poisoner's Handbook
- ^ Risk Assessment (PDF), 2003, archived from the original on January 12, 2012, retrieved January 19, 2013