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This is an index of lists of molecules (i.e. by year, number of atoms, etc.). Millions of molecules have existed in the universe since before the formation of Earth. Three of them, carbon dioxide, water and oxygen were necessary for the growth of life.
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
[16] [17] [18] A molecule may be homonuclear, that is, it consists of atoms of one chemical element, as with two atoms in the oxygen molecule (O 2); or it may be heteronuclear, a chemical compound composed of more than one element, as with water (two hydrogen atoms and one oxygen atom; H 2 O). A molecule is the smallest unit of a substance that ...
For example, the molecule acetylene has molecular formula C 2 H 2, but the simplest integer ratio of elements is CH. The molecular mass can be calculated from the chemical formula and is expressed in conventional atomic mass units equal to 1/12 of the mass of a neutral carbon-12 (12 C isotope) atom.
Chemical substance – Form of matter; List of alchemical substances; List of chemical elements; List of minerals – List of minerals with Wikipedia articles; List of named alloys; List of straight-chain alkanes; Polyatomic ion – Ion containing two or more atoms; Exotic molecule – a compound containing one or more exotic atoms
For example, d-wave or triplet superconductor, or a Fulde–Ferrell–Larkin–Ovchinnikov superconductor. Ferromagnetic superconductor: Materials that display intrinsic coexistence of ferromagnetism and superconductivity. Charge-4e superconductor: A proposed state in which electrons are not bound as Cooper pairs but as quadruplets of electrons.
Colors of a single chemical in different solvents, under visible and UV light, showing how the chemical interacts dynamically with its solvent environmentIn addition to the generic definition offered above, there are several niche fields where the term "chemical substance" may take alternate usages that are widely accepted, some of which are outlined in the sections below.
Chemical classification systems attempt to classify elements or compounds according to certain chemical functional or structural properties. Whereas the structural properties are largely intrinsic, functional properties and the derived classifications depend to a certain degree on the type of chemical interaction partners on which the function is exerted.