Module 6 - 6.4.1 The Nuclear Atom

Question 1

A nucleon is

Answer 1

A proton or a neutron

Question 2

Atomic Number is the number of

Answer 2

protons

Question 3

Mass Number is the number of

Answer 3

nucleons

Question 4

Isotopes are atoms of the same element which contain

Answer 4

• the same number of protons
• but have a varying number of neutrons

Question 5

1 fermi (fm) =

Answer 5

1x10^-15 m

Question 6

The Alpha Particle Scattering Experiment (4)

Answer 6

• current model: Plum Pudding
• Rutherford fired a beam of alpha particles at a thin gold foil
• Thought all the alpha particles would pass straight through the positive “soup” unstopped
• However, some bounced back

Question 7

The Alpha Particle Scattering Experiment Conclusions (3)

Answer 7

• vast majority of the mass of an atom is concentrated within a small volume called the nucleus
• the nucleus has a positive charge
• the atom is mostly empty space

Question 8

Nucleus diameter is roughly
Atom diameter is roughly

Answer 8

1 x 10^-14 m
1 x 10^-10 m

Question 9

All atomic nuclei have – density

Answer 9

the same

Question 10

The 4 fundamental forces are:

Answer 10

• strong
• weak
• gravitational
• electromagnetic

Question 11

The Strong Nuclear Force is (3)

Answer 11

• the force that holds the nucleus together against the electrostatic repulsion of the photons
• acts between nucleons and keeps quarks together
• the gravitational force of attraction between two protons is far too small to counteract the repulsive electrostatic force and so another force is needed

Question 12

Range of Strong Force (4)

Answer 12

• if the force was just attractive, the nucleons would collapse in on themselves, so it must become repulsive at some stage
• is a short range force
• repulsive <0.5fm
• attractive 0.5fm <x< 3fm