2.1.1 atomic structure

What’s an isotope

atoms of the same element with same number of protons but different number of neutrons - diff masses

Whats relative atomic mass

the average mass of one atom of an element compared to 1/12 of the mass of carbon-12 atom

What’s relative isotopic mass

the mass of one isotope compared to 1/12 of the mass of carbon-12 atom

mass number

sum of protons and neutrons

atomic number

total number of protons

Whats empirical formula

the smallest whole number ratio of atoms of each element in a compound

Whats empirical mass

the total mass of all atoms displayed in empirical formulae of a compound

Whats molecular formula

the actual numbers of atoms of each type of element in a molecule

made up of a whole number of empirical units

Equation for moles

moles = mass / mr 

Equation for number of atoms

no of atoms/molecules = moles x 6.02×10²³

Equation for volume of gas

volume = moles x 24dm OR 24000cm

Equation for concentration

concentration = moles / volume

Equation for dilutions

C₁V₁ = C₂V₂

Ideal gas law equation

PV = nRT

How to calculate empirical formula

• find moles by m OR % / mr

• divide by smallest mol

• find ratio

• multiply if ratio is .25< x <.75*

How to calculate molecular formula 

• calculate empirical mass using empirical formula

• divide molecular mass by empirical mass

• use ans to multiply the empirical formula by it