atoms Flashcards
atomic number
proton number - number of protons in the nucleus of an atom
Bigger number - smaller number
mass number
nucleon number - number of protons and neutrons in the nucleus
Ar
relative atomic mass, g/mol
O2 Ar = 16 g/mol
Mr
relative formular/molecular mass
eg MgO = 24.3 + 16 = 40.3 g/mol
relative masses standard
carbon-12 is the standard unit of measurement for the relative masses
amu
carbon amu = 12
1 amu = 1/12 of carbon
Ar definiton
weighted mean mass of an atom of an element compared to 1/12 of the mass of an atom of carbon-12
relative isotopic mass
mass of 1 atom of an isotope relative to 1/12 of the mass of 1 atom of carbon-12
Relative molecular mass, Mr
Relative molecular mass of a compound is the mass of a molecule of the compound relative to 1/12 of the mass of one atom of Carbon-12
Mass spectrometry
Technique used to determine the composition of a substance e.g. isotopes
Can be used to determine the structure of organic molecules
Molar mass
Mass in grams of 1 mole of a substance, g mol-1
Molar gas volume
Volume of 1 mole of a gas at a given temperature and pressure
All gases have this same volume
At room pressure (1 atm) and room temperature (25C), the molar gas volume is 24dm3 mol-1
Avogadros constant
1 mole contains NA 6.02x10^23 atoms/molecules/ions
Empirical formula
Simplest ratio of atoms of each element in the compound
Molecular formula
Actual number of atoms of each element in the compound
