Topic 6 - radioactivity - Radioactivity Decay

Question 1

State 4 types of nuclear radiation

Answer 1

1) alpha particles
2) beta particles
3) gamma rays
4) neutrons

Question 2

What is meant by background radiation

Answer 2

1) radiation that is always present
2) it is in very small amounts and so it’s not harmful

Question 3

Give 4 sources of background radiation

Answer 3

1) rocks
2) cosmic rays from space
3) nuclear weapon testing
4) nuclear accidents

Question 4

How do you measure and detect background radiation

Answer 4

1) photographic film
2) Geiger-Müller counter

Question 5

How is photographic film used to measure radiation

Answer 5

A photographic film turns dark when it absorbs radiation. This is useful for people who work on radiation as the more radiation they are exposed to, the darker the film becomes. Therefore the workers know when they have been exposed to too much radiation.

Question 6

How is geiger-muller tubes used to measure radiation

Answer 6

When the geiger-muller tube absorbs radiation it produces a pulse, which a machine uses to count the amount of radiation. The frequency of the pulse depends on how much radiation is present.

A higher frequency would mean the tube is absorbing a large amount of radiation.

Question 7

What makes up of an alpha particle

Answer 7

Two protons and two neutrons

Question 8

What is the range of an alpha particle though air

Answer 8

A few cm ( normally in the range of 2-10cm )

Question 9

What will block an alpha particle

Answer 9

A piece of paper

Question 10

What will block beta radiation

Answer 10

1) A thin sheet of aluminium

2) Several metres of air

Question 11

What will block gamma radiation

Answer 11

1) several cm of lead
2) a few metes of concrete

Question 12

What type of radiation is the most ionising

Answer 12

Alpha radiation

Question 13

What type of radiation is least ionising

Answer 13

Gamma radiation

Question 14

How does gamma emission affect mass/charge of an atom

Answer 14

Both mass and charge remain unchanged

Question 15

Describe the plum-pudding model of the atom

Answer 15

A sphere of positive charge, with the negativity charged electrons distributed evenly throughout it.

Question 16

Prior to the discovery of the electron what was believed about the atom

Answer 16

The atom was believed to be indivisible

Question 17

Which experiment led to the plum-pudding model being discarded

Answer 17

Rutherford’s alpha-scattering experiment

Question 18

Describe the Rutherford’s experiment

Answer 18

Alpha particles (charge + 2) were fired at a thin sheet of gold foil

Most particles went straight though

Some particles were deflected by small angles (< 90 degrees)

Some particles were deflected by large angles (>90 degrees)

Question 19

What are the conclusions of rutherfords experiment

Answer 19

1) Most of an atom is empty space

2) the nucleus has a positive charge

3) most of the mass is concentrated in the nucleus

Question 20

What happens in the process of beta plus decay

Answer 20

A proton turns into a neutron emitting a position. The position is emitted and the neutron remains in the nucleus.

Question 21

What is beta plus decay

Answer 21

A proton turns into a neutron emitting a position. The position is emitted and the neutron remains in the nucleus.

Question 22

What is the process called when a neutron changes into a proton and an electron

Answer 22

Beta minus decay

Question 23

What effect does beta minus decay have on the mass number and atomic number of an atom

Answer 23

Atomic number +1

Mass number stays the same

Question 24

When alpha decay occurs, what happens to the atomic number and mass number of the atom

Answer 24

Atomic number -2

The mass -4

A new element is made since the atomic number has changed