ATOMS, MOLECULES & STOICHIOMETRY
Atoms, molecules & ions
Atom: smallest indivisible part of element, has neutrons, protons + electrons, can't be changed by chemical reactions (only nuclear reactions ¹⁴N >(cosmic radiation) >¹⁴C)
Molecule: smallest part of element / compound that exists by itself
Ion: charged particle (+/-)

Relative atomic mass RAM: hydrogen, oxygen, carbon scale
hydrogen scale: H atom = lightest atom > given relative mass (RM) of 1 unit (mass of 1 atom of (element/H) x 1.0000)