Development of the Atom

Ancient Greece - Democratus coined the idea of atoms, particles so smal they could no longer be divided

Plum Pudding Model of the atom - An atom is believed to be a ball of positive charge, containing inside of it smaller dots of negative charge

Rutherford experiment - Fired alpha particles (positively charged) at a thin layer of gold sheet

Results - Most particles went straight through meaning most of an atom is empty space

Some particles deflected or even bounced back meaning the positive charge is very comparitevely small but is at the centre of the atom

Nuclear model - A central positive nucleus orbited by electrons

Bohr - Shells

Protons

Electrons