History of the atom

• What is the difference between the plum pudding model and the nuclear model?

  nuclear model mostly empty space, mass concentrated at centre, electrons orbit nucleus at set distance, electrons and nucleus separate
• What change did Bohr make to the nuclear model?

  electrons orbit nucleus at set distance from nucleus
• How did evidence from alpha particle scattering experiment change model of atom?

  most alpha particles passed straight through gold foil so mass concentrated at centre. Some alpha particles deflected so atom has positively charged nucleus
• How did Chadwick's work lead to better understanding of isotopes?

  Chadwick discover neutrons. isotopes have same number of protons. but different number of neutrons