The Mole

-equal volume of different gases has a constant ratio
ex oxygen:hydrogen=16:1
   carbon dioxide:hydrogen=22:1
-expressed by comparing it to the mass of another object


Avogadro's Hypothesis
Equal volume of different gases at the same temperature and pressure have the same number of particles.
If they have the same number of particles, the mass ratio is due to the mass of the particles.


Atomic Mass
Mass of 1 atom of the element in atomic mass units(amu or u or Dalton)
ex fluorine=19.0 amu


Formula Mass
All the atoms of a formula of an ionic compound(in amu)
ex potassium fluoride (KF)   39.1+19.0=581amu


Molecular Mass
All the atoms of a formula in a covalent compound (in amu)
ex carbon dioxide(CO2) = 12.0+16.0×2=44.0 amu


Molar Mass
Atomic/Molecular/Formula mass of any pure substance(in grams per mole)
ex 1mole of oxygen=16.0 g/mol
   1mole of carbon =12.0 g/mol
(same number of particles)


Avogadro's Number
The number of particles in 1 mole of any amount of substance is
6.022×10^23 particles/mol


The mole is extremely important to chemists because it allows them to count atoms and molecules.