Rutherford’s alpha scattering experiment.

source of

alpha particles

thin gold foilphotographic film

beam of particles most pass

straight

through

1 in 20 000 deflected

Rutherford’s explanation.

atoms of gold

in gold foil

Path of an particle

nucleus of

gold atom

All these particles pass straight through the empty space that makes up most of the atom.

This particle

passes close enough to nucleus to be repelled

As particles are positively charged, the nucleus must contain positively

charged protons.

atoms of gold

in gold foil

nucleus of

gold atom

As only 1 in every 20 000 particles are repelled the nucleus must be very small.

Size of the nucleus.

Rutherford’s model of the atom.

Tiny nucleus containing the positively charged protons.

Rest of atom is mostly empty space. The negatively charged

electrons are spinning round the nucleus.