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Chemistry - The History of the Atom - Coggle Diagram
Chemistry - The History of the Atom
John Dalton
described atoms as solid spheres
couldn’t be divided
different spheres made up the different elements
J J Thomson (1897)
discovered electrons
PLUM PUDDING MODEL
positive charge randomly spread throughout atom
random electrons
Ernest Rutherford (1911)
alpha particle scattering experiments
fired positively charged alpha particles at a thin sheet of gold
some were deflected more than expected
some bounced back
most went through - empty space
from Plum Pudding Model
expecting particles to pass straight through / slightly deflected
because positive charge of each atom was very spread out
New Idea
NUCLEAR MODEL
must be a positively charged part of atom
positive nucleus in centre
cloud of electrons surround nucleus
Niels Bohr
scientists realised
electrons in a ‘cloud’ around nucleus would attract to it - cause atom to collapse
New Nuclear Model
electrons orbit nucleus in fixed shells
James Chadwick
discovered neutrons