SPM Form 4: Chemical Formulae and Equations (Checklist)

• Relative atomic mass, A_r, is defined as the mass of one atom of an element relative to 1/12 of the mass of an atom of carbon-12, which has a mass of 12.00 atomic mass units.
• Relative molecular mass, M_r, is defined as the mass of one molecule of an element or compound relative to 1/12 of the mass of an atom of carbon-12, which has a mass of 12.00 atomic mass units.
• Empirical formula is a formula showing the simplest ratio of atoms present.
• Molecular formula is a formula showing the actual number of atoms of each element present in one molecule.
• Chemical equation is a representation of a chemical reaction in words or using chemical formulae.
• The molar mass is the mass of one mole of a sample.                
• Molar volume is the volume of one mole of a substance. The molar volume of an ideal gas at STP is 22.4 L/mol.
• Avogadro's constant is the number of particles found in one mole of a substance. Avogadro’s constant=6.0221 x 10²³ particles per mole.
• Avogadro’s Law: equal volume of all gases measured under the same conditions of temperature and pressure contain equal numbers of molecules.