P1.1.2 - The Model Of The Atom 2 Flashcards
What did Ernest Rutherford first discover?
Some materials emit particles
What are alpha particles?
Particles that are emitted by some materials
What is the charge of an alpha particle?
Positive
When was the alpha particle discovered?
1899
Who helped Rutherford with his gold foil experiment?
Hans Geiger and Ernest Marsden
How did Rutherford explain the results of his experiment?
He suggested that an atom is made of a tiny, positively charged nucleus that is surrounded by electrons.
What was the rutherford model?
An atom containing a nucleus with randomly encircling electrons
What happens when alpha particles hit a nucleus?
They bounce back
If an alpha particle slightly veers off when going through an atom, what does this suggest?
There is a powerful charge somewhere in the atom
If most of the fired alpha particles went through the atom, what does this suggest?
The atom is mostly empty
If some of the alpha particles bounced back from the atom, what does this suggest?
There is something small and heavy in the atom
What did Niels Bohr suggest?
That electrons can only move in fixed orbits
What are Electron shells?
The fixed pathways that electrons move in?
When did Niels Bohr introduce electron shells?
1913
What is the diameter of an atom?
10 to the power of -10
What are molecules?
A collection of atoms, strongly joined together or bonded
Why was the apparatus in the Rutherford experiment placed in a vacuum chamber?
To stop air particles from absorbing the alpha particles
How did they conduct the Rutherford model?
They used a detector consisting of a microscope focused on a small glass plate. The small glass plate was on the gold foil that had alpha particles shot at it from a small lead box. Every time an alpha particle hits the plate a light shows up that the scientists can count. The scientists used the detector to different positions and at each position they counted the amount of light showing up.
