Isomorphism (crystallography)
In chemistry, isomorphism has meanings both at the level of crystallography and at a molecular level. In crystallography, crystals are isomorphous if they have identical symmetry and if the atomic positions can be described with a set of parameters (unit cell dimensions and fractional coordinates) whose numerical values differ only slightly.[1]
Molecules are isomorphous if they have similar shapes. The
In order to form isomorphous crystals two substances must have the same chemical formulation (i.e., atoms in the same ratio), they must contain atoms which have corresponding chemical properties and the sizes of corresponding atoms should be similar. These requirements ensure that the forces within and between molecules and ions are approximately similar and result in crystals that have the same internal structure. Even though the space group is the same, the unit cell dimensions will be slightly different because of the different sizes of the atoms involved.
Mitscherlich's law
Mitscherlich's law of isomorphism, or the law of isomorphism, is an approximate law suggesting that crystals composed of the same number of similar elements tend to demonstrate isomorphism.[3]
Mitscherlich's law is named for German chemist Eilhard Mitscherlich,[4] who formulated the law and published it between 1819 and 1823.[5]
According to
See also
- Asterism (gemology)
- Polymorphism (materials science)
- Goldschmidt tolerance factor
- Solid solution
- Vegard's law
References
- ISBN 978-1-891389-77-1.
- ISBN 0-19-855370-6. pp 186–186 in 3rd. edition
- ^ "Mitscherlich, Eilhard". Complete Dictionary of Scientific Biography. Encyclopedia.com. 2008.
- ISBN 9780841233454.
- ISBN 9780674396593.
- ISBN 978-2881245695. Retrieved 12 March 2020.