AS Chem chapter 3

chapter 3 chem

Unified Atomic Mass Unit

one-twelfth of the mass of a carbon-12 atom

Relative Atomic Mass, A_r

weighted average mass of the atoms of an element compared to the unified atomic mass unit

Relative Isotopic Mass

average mass of particular isotope of an element compared to the unified atomic mass unit

Formula unit

The simplest formula for a covalent giant structure or an ionic giant structure

Relative molecular mass, M_r

weighted average mass of a molecule in a given sample of that molecule compared to the unified atomic mass unit

Relative formula unit, M_r

weighted average mass of one formula unit compared to the unified atomic mass unit (used for compounds containing ions)

Water of crystallisation

specific number of moles of water associated with a crystal structure

hydrated compounds

compounds that contain water of crystallisation

anhydrous compounds

compounds that do not have water of crystallisation

Relative isotopic abundance

proportion of one particular isotope in a mixture of isotopes

Molar mass, M

mass of a mole of a substance in grams, g mol^-1