# Atomic masses

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• Atomic masses
• relative atomic/ isotomic mass
• the mass of an atom of an element /isotope compeared to the mass of 1/12 of carbon 12
• relative abundance
• (reltive abundance x isotope) + (reltive abundance x isotope)/100
• e.g (75 x 35)+(25 x 37)/100 = 35Cl
• relative molecular mass the Mr is the weight mass of an molecule compared to 1/12 of the mass of carbon
• relative formulae mass = the Mr of all the molecules added together
• formulae
• mass/no of mols = relative atomic mass
• mass/relative atomic mass = no of mols
• no of mols x Mr = mass
• concentration x volume/ 1000 = no of mols in dm3 or without the 1000 if volume already in Dm3
• volume = no of moles / volume
• concentration = no of moles/ concentration
• empirical formulae= first do M/Mr then apply this ratio you get to the elements you have to get the empirical formulae
• empirical formulae the lowest no ratio of elements in a substance
• acids and bases
• acid= is a spices that is a proton doner = H+
• ate(with oxygen) ide (without oxygen)
• cation = +ive anion= -ive