# The elementary substances

## Definition

An elementary substance is a chemical substance whose molecules (or lattices) are only formed out of one kind of atoms.

## Metals

Metals are formed of lattices in their solid state, the atoms are simply piled up like marbles in a box. The fundamental structural unit is the single atom. Here are for instance formulas of metals:

 Copper: Cu Iron: Fe Mercury: Hg

- Metals have a particular metallic luster - Metals conduct electrical current - Metals conduct heat

## Nonmetals

Most nonmetallic elementary substances are made out of molecules. In the case of noble gases, the "molecules" are made out of one single atom ("monoatomic molecules"). In a few rare cases, the atoms are bound in such a complicated way that a molecular structure can no more be distinguished. (Red phosphorous, graphite carbon , diamond carbon)

- Nonmetals (except C) conduct electricity poorly - Nonmetals conduct heat poorly Formulas: - The number of atoms in a molecule is written as a small number to the right of the symbol. - The number of molecules is written before the formula.

$3H_2$

$H_2+2I_2$

$3S_8+2I_2$