Chapter 24 Particle Physics

Question 1

Describe how the alpha particle scattering experiments provide evidence for the existence, charge and size of the nucleus?

Answer 1

Most of the alpha particles passed straight through showing that most of the atom is empty space
Very few were deflected by the nucleus showing that it has a positive charge and is very small 10⁻¹⁴m

Question 2

What are the three forces acting on protons and neutrons in a nucleus?

Answer 2

Gravitational force
Follows an inverse square law so has a long range

Electrostatic force
Follows an inverse square law so has a long range

Strong nuclear force
Has a very short range of about 10⁻¹⁴m

Question 3

What is the quark model for beta+ decay?

Answer 3

proton to neutron

Question 4

What is the quark model for beta- decay?

Answer 4

neutron to proton

Question 5

What is the force responsible for beta- decay?

Answer 5

Weak nuclear force

Question 6

What are hadrons?

Answer 6

Particles made from quarks

Question 7

What are fundamental particles?

Answer 7

Fundamental particles that cannot be subdivided, such as quarks.

Question 8

What is a lepton?

Answer 8

A member of the subatomic particles which respond to weak force, gravitational force and electromagnetic force

Electron
Positron
Electron neutrino
Muon
Muon neutrino
Tau
Tau neutrino

Question 9

Why is energy release when a single nucleus decays via beta minus decay?

Answer 9

There is a decrease in mass and the binding energy increases.

Question 10

What are baryons?

Answer 10

Particles made of only 3 quarks
such as protons, neutrons and lambda