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John Dalton discovered that all elements always breakdown to the same components known as atoms. Atoms cannot be created or destroyed. -
JJ Thomson discovered the electron. His model represents a plum cake or blueberry muffin showing a positive "cake" embed by negatively charged electrons. -
Ernest Rutherford was JJ Thomson's student. He discovered that atoms are mostly empty space with nuclei that are very small. -
Niels Bohr is also one of JJ Thomson's students. He discovered that electrons orbit the nucleus and can jump from level to level. He also discovered that electrons travel in a wave like pattern. -
James Chadwick later proved the existence of neutrons (which are neutrally charged).