What did John Dalton do?

JOHN DALTON: 1- Published his ideas in 1803 2- All matter was made of tiny spheres that cant be divided - atoms JJ THOMSON: 1- Nearly 100 years later, discovered electrons 2- Plum pudding model: ball of + charge, - electrons embedded ERNEST RUTHERFORD: 1- Positive charged alpha particles fired at thin gold foil 2- most went through: mostly empty space 3- few scattered in all directions: positively charged nucleus concentrated at atoms centre NIELS BOHR: 1- Did calculations& experiments: electrons orbit the nucleus in shells at fixed distances FURTHER EXPERIMENTS: 1- Protons: positive charge JAMES CHADWICK: 1- 1932, found evidence for mass in nucleus with no charge - neutrons