Radioactivity

Question 1

What does the nucleus of an atom contain

Answer 1

Protons and neutrons

Question 2

What is another name for number of protons in a nucleus

Answer 2

Atomic number

Question 3

What is the mass number

Answer 3

The mass number is the total number of protons and neutrons in the nucleus

Question 4

What are isotopes

Answer 4

Isotopes are atoms of the same element with the same number of protons but different number of neutrons

*do not forget atom

Question 5

What are the two common isotopes of carbon?

Answer 5

Carbon 14 and Carbon 12

Question 6

What does radioactive mean ?

Answer 6

An atom is radioactive when the nucleus is unstable, so it decays and emits radiation

Question 7

Nuclei are affected by physical conditions like temperature

TRUE or FALSE

Answer 7

FALSE

Nuclei are completely unaffected by physical conditions

Question 8

What are the three types of radiation ?

Answer 8

Alpha , Beta and Gamma radiation

Question 9

List four main sources of radiation

Answer 9

Substances on Earth
- rocks,soil

Cosmic rays
-mostly from the sun

Living things
- a little in all living things

Radiation from human activity
-nuclear waste

Question 10

Alpha particles are made up of
_ protons and _ neutrons

Fill in the gaps

Answer 10

2

Question 11

What can ionising radiation be deflected with ?

Answer 11

Photographic film
or
a Geiger-Muller detector

Question 12

Are alpha particles positively or negatively charged ?

Which enables them to be deflected by which fields ?

Answer 12

Positively

Electric and Magnetic fields

Question 13

What is a beta particle ?

Answer 13

A beta particle is an electron which has been emitted from the nucleus of an atom when a neutron turns into a proton and an electron.

Question 14

What charge are Gamma rays ?

Answer 14

They have no charge

Question 15

What are Alpha particles
Beta particles
And Gamma rays
Stopped or blocked by ?

Answer 15

Alpha particles - skin or paper
Beta particles - thin metal (aluminium)
Gamma rays- thick lead or thick concrete

Question 16

Who suggested that atoms were spheres of positive charge with tiny electrons stuck in them like a plum pudding

Answer 16

J J Thompson

Question 17

What does Rutherford’s nuclear model of an atom say ?

- give 4 points

Answer 17

1. Most of an atom is empty space
2. The nucleus must be small
3. It must be positive (the nucleus)
   And
4. Most of the mass must be concentrated at the centre

Question 18

What is half life?

Answer 18

Half life is the time it takes for a radioactive material to lose half of its radioactivity.

Question 19

Why is the activity of radioactivity measured in half life?

Answer 19

The activity or radioactivity is measured in half life because the activity never reaches zero

Question 20

Give three uses of nuclear radiation

Answer 20

Medicinal uses
Archeological uses
Industrial tracers I

Question 21

Which radiation is used to treat cancer

Answer 21

Gamma rays

Question 22

Name three safety precautions required l when working with radioactive materials

Answer 22

1. Never allow skin contact with the source
2. Avoid looking directly at the source
3. Store in a sealed lead box whenever not in use

Question 23

Name three extra safety precautions

Answer 23

1. wear lead aprons and stand behind lead screens during procedures
2. Wearing full protective suits
3. using remote controlled robot arms

Question 24

What is nuclear fission?

Answer 24

Nuclear fission is the splitting of an atom which releases energy

Question 25

When uranium-235 splits in to two it will form ?

Answer 25

Two new daughter nuclei

Question 26

The energy released when a nucleus is in the form of ___ energy

Answer 26

Kinetic energy

Question 27

The kinetic energy is converted to ___ energy in the reactor by ____ with other atoms

Answer 27

Heat energy

Collisions

Question 28

What does the moderator usually do inside a nuclear reactor

Answer 28

It slows down neutrons so they can successfully collide with uranium nuclei (and sustain the chain reaction)

Question 29

What are control rods made of

Answer 29

Boron

Question 30

What do the control rods do ?

Answer 30

They limit the rate of fission by absorbing excess neutrons.