P7 Radioactivity

Question 1

Why are radioactive isotopes unstable?

Answer 1

Becuase they have a heavy nucleus

Question 2

What is nuclear decay?

Answer 2

Radioactive isotopes contain a heavy nucleus so they emitt particles and energy to become stable.

Question 3

What are the characteristics of Alpha particles?

Answer 3

• Similar to Hellium nucleus (2+ charge)
• Slower than Beta and Gamma
• Lowest penetration (can be stopped by paper)
• Highest Ionisation

Question 4

What are the characteristics of Beta particles?

Answer 4

• Fast moving electron
• Negative charge
• 1.5x10^8 m/s
• Higher penetration than alpha
• Moderate ionisation

Question 5

What are the characteristics of Gamma particles?

Answer 5

• EM wave emitted from nucleus
• No charge
• 3x10^8 m/s
• Highest penetration level
• Least ionisation

Question 6

What can alpha particles be stopped with?

Answer 6

Few centimeters of paper (alpha particles have the lowest penetration)

Question 7

What can beta particles be stopped with?

Answer 7

1 metre of Aluminium

Question 8

What can Gamma particles be stopped with?

Answer 8

Several centimeters of lead or 1 metre concrete (highest penetration)

Question 9

What is the nuclear equation for Alpha decay?

Answer 9

Radioactive element – > Helium + Other element

Question 10

What is the nuclear equation for Beta decay?

Answer 10

Beta Element — > New element (contains the 1 less protons than the original element) + Electron

Question 11

What is the nuclear equation for Gamma decay?

Answer 11

Element (with more energy) —> Same element (with less energy)

Question 12

How can radioactivity be detected?

Answer 12

By using a photographic film or Gieger-Müller tube

Question 13

What is activity measured in?

Answer 13

Becquerel (Bq)

1Becquerel = 1 decay per second

Question 14

What is activity?

Answer 14

The number of decays per second.

Question 15

How do you calculate activity?

Answer 15

Activity = number of decays / time

Question 16

What is background radiation?

Answer 16

It is a low-level ionising radiation that is produced all the time.
most of this radiation occurs naturally

Question 17

What are the 4 types of background radiation?

Answer 17

• Radon gas
• Cosmic rays
• Internal radiation
• Man-made factors

Question 18

How dose radon gas cause background radiation?

Answer 18

Raditation emitted from rocks e.g. granite account for 50% of natural radiation.

Question 19

How do cosmic rays cause background radiation?

Answer 19

Supernoval explosions in stars cause cosmic rays

Question 20

What is internal radiaiton?

Answer 20

Radiation caused by radioactive sources present inside our bodies.

Question 21

What man-made factors cause background radiations?

Answer 21

• Nuclear power stations
• Nuclear testing
• Medicine (gamma rays for radiotherapy)

Question 22

What is half-life?

Answer 22

The average time taken to reduce the number of radioactive nuclei into a half

Question 23

How do you calculate the number of nuclei after a specific time?

Answer 23

Final number of nuclei = Original number of nuclei / 2^number of half-lives

Question 24

What is an alpha particle?

Answer 24

A particle made of 2 protons and 2 neutrons.

(can also be named a helium nucleus)

Question 25

What is a Beta Particle?

Answer 25

A high speed electron ejected from the nucleus as a neutron turns into a proton

Question 26

What is gamma decay?

Answer 26

Electromagnetic radiation from the nucleus

Question 27

What is the nature of an alpha decay?

Answer 27

Particle

Question 28

What is the nature of a beta decay?

Answer 28

Particle

Question 29

What is the nature of gamma decay?

Answer 29

Wave

Question 30

What is the electrical charge of alpha decay?

Answer 30

+2

Question 31

What is the electrical charge of beta decay?

Answer 31

-1

Question 32

What is the electrical charge of gamma decay?

Answer 32

0