.The structure of matter In late 1800s, electrons(negative charge) proton(positive charge) 1836 times as heavy as electron neutron(uncharged, 1932) In 1904 Thomson the positive charge were spread through the atom In 1909 Rutherford a particle (helium i)passed through atom large deflections(大角度散射) 1911. Rutherfords planetary model the electrons revolved about the nucleus in various orbital