------------------------------------------------------------------------------------------------------------------- Chemistry
relative atomic mass - the ratio of the average mass of one atom of an element to one twelfth of the mass of an atom of carbon-12
first ionisation energy - the energy required to remove the most loosely held electron from one mole of gaseous atoms to produce 1 mole of gaseous ions each with a charge of 1+
e.g. Mg(g) -> Mg+(g) + e-
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