Chemical element
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A chemical element is a species of atom defined by its number of protons. The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8: each oxygen
Metals (blue) and metalloids (green) in the periodic table
John Dalton's list of atomic weights & symbols, 1808
Estimated distribution of dark matter and dark energy in the universe. Only the fraction of the mass and energy labeled "atoms" is composed of elements.
Robert Boyle, c. 1740
Chemical species
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A chemical species is a type of matter that displays a specific, uniquely identifying, set of properties. A systematic chemical name can be used to refer to a chemical species.
Chemical element
…A chemical element is a species of atom defined by its number of protons. The number of protons is called the atomic number of that element. For example, oxygen has an atomic number…
Table salt, formally sodium chloride (NaCl), is an example of a crystalline ionic chemical species. The crystal matrix of table salt is formed from two chemically distinct ions: Na+ and Cl- each of which are also chemical species. Unless otherwise required by context, we assume that Na and Cl appear in their natural abundance ratio in these chemical species