Chemistry - Structure 1: Counting particles by mass, the Mole.

Mole

S.I unit for substance amount, contains the same number of particles as relative to the number of particles of carbon atoms in 12g of C-12.

Avogrado’s constant

6.02 × 10²³ particles/mol.

Relative atomic mass (Ar)

The weighted average mass of naturally occurring isotopes relative to 1/12 of the mass of a C-12 atom.

= weighted average mass of one atom of an element ÷ 1/12 mass of one atom of C-12

Relative formula mass

The sum of the weighted average of the atoms of an element in a formula unit relative to 1/12 of the mass of a C-12 atom.

Molar mass

Relative atomic mass/formula mass expressed (g/mol.).

number of mol. = mass/g ÷ molar mass/mol.

Percentage by mass

The amount of each atom as a percentage of the total mass.