C1.5 History of the Atom Flashcards
What was John Dalton’s idea?
➢ Suggested atoms cannot be divided or split
➢ And in chemical reactions, the atoms re-arranged themselves and combined with other atoms in new ways
What did J.J Thomson discover?
The electron
How did Thomson discover the electron?
By applying high voltages to gases at low pressure
Who discovered the plum pudding model?
J.J thomson
What is the plum pudding model?
Tiny electrons are evenly spread across an atom, the atom is made up of a positive blob
Who disapproved of the Plum pudding model?
Rutherford
What was Rutherford’s experiment?
Firing alpha particles at gold foil
What were the observations Rutherford saw during the experiment?
Most of the alpha particles passed straight through
A small number of alpha particles were deflected back
Small number of alpha particles came straight back off the foil
What do most of the alpha particles going straight through the foil suggest?
The atom is mostly empty space
What does the small number of alpha particles being deflected show?
Shows there is a concentration of positive charge in the atom
What do the alpha particles coming back, show?
Suggests the positive charge and mass concentrated in a tiny volume
Who discovered the proton?
Rutherford
What did Niels Bohr discover?
Discovered energy levels for the electrons
