C1.5 - History Of The Atom (Finished) Flashcards
What were John Dalton’s ideas about atoms?
- Substances were made up of them, they were tiny solid spheres
- Each chemical had it’s own atoms that differed in mass
- They could not be divided or split
What did John Dalton suggest atoms did in chemical reactions?
Atoms re-arranged themselves and combined with different atoms in many ways
What did J JThomson discover?
The electron
What was Thomson’s model like?
There were tiny negatively charged electrons embedded on a cloud of positive charge (plumb pudding model)
What did the gold foil experiment discover?
The nucleus
How was the nucleus discovered?
Alpha particles were fired at thin gold foil and expected them to pass through. But they were deflected and some came back
What model was presented for the gold foil experiment?
Electrons orbited a nucleus of dense positively charged protons
Why did Niels Bohr suggest electrons orbited in shells?
Light given out when atoms were heated only had specific amounts of energy
Why were neutrons predicted?
There was missing mass in atoms counting only protons ( and electrons)
Who discovered the nucleus?
Ruethford’s students
Why were alpha particles expected to pass through the gold foil?
Because the positive charge of the atom was thought to be very spread out through the pudding
What model of the atom did Bohr suggest?
The electrons were orbiting the nucleus of dense positive charge at set distances in fixed energy levels
