Events
DEMOCRITUS
Named smallest piece of matter " Atomos " meaning " not to be cut "
They were small, hard particles that were all made of the same material but different shapes and sizes
All atoms were infinite in number. always moving and cable of joining togetherJAMES CHADWICK
His neutrons have no electrical charge
His neutrons have a mass nearly equal to the mass of a proton
The unit of measurement for subatomic particles is the the " atomic mass unit " ( amu )JOHN DALTON
Matter consists of small particles called atoms
All elements are made up of atomsERNEST RUTHERFORD
The atom is composed of mostly empty space
The atom is small, dense, positively charged nucleus containing most of the atoms massSome
event
happened
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