Radiactive Decay

Question 1

State the four types of nuclear radiation

Answer 1

Alpha radiation
Beta radiation
Gamma radiation
Neutron Radiation

Question 2

What is meant by background radiation?

Answer 2

radiation all around us that is always present

Question 3

Give the sources of background radiation

Answer 3

Food
Nuclear Power
Cosmic Rays
Medical
Radon Gas
Ground/Buildings

Question 4

How do you measure and detect background radiation?

Answer 4

Photographic film

Geiger Müller Counter

Question 5

How is photographic film used to measure radiation?

Answer 5

A photographic film turns dark when it absorbs radiation. Helpful for those who work on radiation as the darker the film, the more radiation they know they have been exposed to.

Question 6

How are 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 high frequency would mean the tube is absorbing a large amount of radiation.

Question 7

What is an alpha particle

Answer 7

particle made of 2 neutrons, 2 protons

also known as a helium nucleus

Question 8

What is an alpha particles stopping power

Answer 8

can travel a few cm in air, stopped by paper/skin

Question 9

what is a beta particles stopping power

Answer 9

can travel a few m in air, stopped by aluminium foil

Question 10

what is the stopping power for gamma particles

Answer 10

can travel many kms in air, stopped by thick concrete or led

Question 11

label the types of radiation staring from the most to least ionising

Answer 11

most-alpha
middle-beta
least-gamma

Question 12

How does gamma emission affect the mass/charge of an atom?

Answer 12

Both mass and charge remain unchanged.

Question 13

Describe the plum-pudding model of the atom

Answer 13

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

Question 14

Which experiment led to the plum-pudding model being discarded?

Answer 14

Rutherford’s gold foil/ alpha scattering experiment

Question 15

What is the name given to the model of the atom before Rutherford’s experiment ?

Answer 15

The Bohr

Question 16

Describe Rutherford’s experiment

Answer 16

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

Most particles went straight through

Some particles were deflected by small angles

A few particles were deflected by large angles

Question 17

What are the conclusions of Rutherford’s experiment?

Answer 17

Most of an atom is empty space

The nucleus has a positive charge

Most of the mass is concentrated in the nucleus

Question 18

What happens in the process of beta plus decay?

Answer 18

A proton turns into a neutron and a positron

Question 19

What happens during Beta Minus Decay

Answer 19

a neutron turns into a proton and electron

Question 20

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

Answer 20

The atomic number decreases by 2

The mass number decreases by 4

A new element is made since the atomic number has changed

Question 21

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

Answer 21

The mass number stays the same as the total number of neutrons and protons hasn’t changed (one has just turned in the other).

The atomic number increases since there is one more proton