Atoms, ions & compounds

• Relative isotopic mass —> mass of an atom of an isotope of the element compared with 1/12th the mass of an atom of 12C
• Relative atomic mass —> Weighted mean mass of an atom of an element compared to 1/12th the mass of an tom of 12C
• Relative molecular mass —> Weighted mean mass of an molecule of the compound compared to 1/12th the mass of an atom of 12C
• Relative formula mass —>Weighted mean mass of a formula unit of the compound compared to 1/12th the mass of an atom of 12C
• Empirical formula —> The simplest whole number ratio of each element in a compound.
• Molecular formula —> actual number of atoms of each element in a molecule. Always a multiple of the empirical formula