{Year 2} Chapter 10 - Evidence for the Nucleus (Up to page 178)

Question 1

Describe the apparatus used by Marsden and Geiger when they carried out the Rutherford Scattering experiment

Answer 1

Alpha emitting source in long thin lead-lined box // Gold foil thinly hammered into a sheet in the line of fire of the alpha particles // Fluorescent screen under a microscope which would flash every time an alpha particle hit it that was moved through many many angles over the course of the months in which the experiment took place

Question 2

Why was the chamber made to be a vacuum in the Rutherford Scattering experiment?

Answer 2

So that the alpha particles could travel without being stopped by the air

Question 3

What were the conclusions that Rutherford drew from his experiment?

Answer 3

That the atom has a very small positively charged nucleus, which is what was responsible for the repulsive force on the positively charged alpha particle // that the nucleus is much smaller than the atom // That the nucleus holds almost the entirety of the atom (figured this out from the conservation of momentum - the larger alpha particle would knock a small nucleus out of the way)

Question 4

What is a femtometer?

Answer 4

The most common measurement used for the size of an atom, it is 1m x 10^-15

Question 5

What is the equation for energy expended for a particle to reach its closest distance of approach?

Answer 5

E = Charge of particle x Charge of nucleus / 4 x Pi x Permittivity of free space x radius