Atom history

• In 1897, JJ Thomson discovered that cathode rays were negatively charged particles called electrons.
• Thomson's model suggested that atoms are like balls made up of positive charge with negative electrons embedded inside them.
• Electron shells surround the nucleus of an atom.
• Rutherford found that most of the mass was concentrated at the center of an atom, leading him to propose his nuclear model.
• The first electron shell can hold two electrons, while subsequent shells have increasing capacities (up to eight).
• Atoms tend to lose or gain electrons until they reach a stable state where their outermost shell is full.
• The nuclear model suggests that all the protons and neutrons are located in the nucleus of an atom.
• 1897-JJ Thomson discovered the plum pudding model
• JJ concluded that the positively charged protons were located in the middle whilst electrons surround them
• in 1911 Rutherford discovered the nucleus and how atoms have a central positively chareged nucleus with most of the mass
• Ernest tested the plum pudding model made by Thomson
• In 1915 Bohr improved Rutherfords model using mathematical ideas he found electron shells occupy around the nucleus
• John dalton 1766-1844 found atoms of different element are different from on another