History of the atom Flashcards
Who was the first scientist to theorise about atoms?
John Dalton
What was Dalton’s model called and what did it look like?
It was called the billiard ball model and it said atoms look like solid, indivisible spheres.
Who discovered electrons?
JJ Thomson
What was Thompson’s model called and what did it look like?
It was called the plum pudding model and it looked like a positively charged cloud with negatively charged electrons scattered inside, allowing the atom to maintain neutral charge.
Who discovered the nucleus?
Rutherford, Geiger, and Marsden
How was the nucleus discovered?
Gold foil experiment
What was the gold foil experiment?
Rutherford sent a beam of Alpha particles at a thin piece of gold.
When some of the particles rebounded, Rutherford concluded that most of the atom is empty space
The nucleus must be positive as it repels positive particles. He called these protons.
Who discovered electrons in shells?
Niels Bohr
How were electrons in shells discovered?
Atoms that give out light when heated have electrons that electrons change energy levels in their shells.
Who discovered neutrons?
James Chadwick
How were electrons theorised to exist?
Atoms were missing mass that wasn’t coming from protons or electrons?
