Radioactivity

Question 1

How did Rutherford workout that atoms were mostly empty space

Answer 1

He shot alpha particles at gold foil and some were deflected a lot

Question 2

What is the charge of a proton

Answer 2

+1

Question 3

What is the charge of a neutron

Answer 3

0

Question 4

What is the charge of an electron

Answer 4

-1

Question 5

What happens to an atom if it loses an electron

Answer 5

It becomes ionised

Question 6

What is ionising radiation

Answer 6

Radiation which can knock electrons out of atoms

Question 7

What is an isotope

Answer 7

Different forms of the same element which have a different number of neutrons but the same number of protons

Question 8

What is radioactive decay

Answer 8

Unstable isotopes decay into other elements and give out radiation to become more stable

Question 9

Name 3 types of ionising radiation

Answer 9

Alpha, beta, gamma

Question 10

What is alpha radiation

Answer 10

Alpha particle ( 2 neutrons 2 protons) is emitted by a nucleus

Question 11

How strong is alpha radiation

Answer 11

It has slow penetration power, extremely ionising

Question 12

What is a beta particle

Answer 12

Beta- , is a fast moving electron
Beta+ , is a fast moving positron

Question 13

How strong are beta particles

Answer 13

Moderately ionising, moderate penetration power.

Question 14

How strong are gamma rays

Answer 14

Strong penetration power, weakly ionising, can be absorbed by thick sheets of lead or concrete

Question 15

What is lost in alpha decay

Answer 15

Mass number decreases 4, atomic number decreases 2

Question 16

What is lost in beta minus decay

Answer 16

Atomic number increases by 1

Question 17

What is lost in beta plus decay

Answer 17

Atomic number decreases by 1

Question 18

What is the half life

Answer 18

The average time taken for the number of radioactive nuclei in an isotope to halve

Question 19

How do you measure half life on a graph

Answer 19

Graph of activity against time, half life is found from the graph by finding time interval corresponding to a halving of the activity on the vertical axis

Question 20

What is background radiation

Answer 20

Low level radiation that is always around us

Question 21

Where can background radiation come from

Answer 21

1. Air
2. Some foods
3. Rocks
4. Cosmic rays
5. Human activity

Question 22

What is exposure to radiation called

Answer 22

Irradiation

Question 23

How do you reduce the effects of irradiation

Answer 23

1. Lead lined boxes
2. Barriers
3. Being in different room

Question 24

What is contamination

Answer 24

Unwanted radioactive atoms getting onto an object

Question 25

What happens if contaminating atoms decay

Answer 25

They release harmful radiation

Question 26

How does radiation damage cells

Answer 26

By ionisation, which can either mutate cells or in worse case cause complete tissue damage

Question 27

Name 3 uses of radiation

Answer 27

1. Fire alarms 2. Sterilisation 3. Tracers & thickness gauges

Question 28

What is a tracer used for

Answer 28

Injecting into a patient and being followed to detect medical conditions

Question 29

What is a PET scan

Answer 29

A scan where a tracer can be used to find the exact location of tumours by placing the tracer in food and waiting until it reaches viral organs

Question 30

What is nuclear fission

Answer 30

Neutron is fired at uranium 235. Neutron is absorbed and uranium becomes even more unstable. When the U 235 atom splits it forms 2 daughter nuclei and energy is released. The new nuclei are radioactive. Every time it splits it also releases 2 or 3 more neutrons. Causing a chain reaction

Question 31

How are chain reactions controlled in reactors

Answer 31

1. The uranium containing fuel rods are placed in a moderator to slow down the fast neutrons. 2. Boron control rods limit the rate of fission by absorbing excess neutrons.

Question 32

How does a nuclear power station work?

Answer 32

The energy created from fission is used to heat water into steam and turn into kinetic energy

Question 33

What is nuclear fusion

Answer 33

2 light nuclei collide at high-speed and fuse to create a large heavier nucleus, and release lots of energy

Question 34

Why is fusion hard to achieve

Answer 34

It is only possible at high temperatures and pressures (10000000°C)

Question 35

What are the positives of nuclear power

Answer 35

1. Safe 2. Reliable 3. Clean energy source 4. Lots of energy

Question 36

What are the negatives to nuclear power

Answer 36

1. Waste is hard to dispose of 2. Pollution is possible 3. Catastrophes 4. Cost is high

Question 37

Why does nuclear fusion require lots of energy

Answer 37

To break the strong electrostatic bonds between protons to fuse the 2 nuclei