Radioactivity

Question 1

How can a nuclei become stable?

Answer 1

By radioactive decay. This releases radiation and turn into other elements.

Question 2

Is radioactive decay controlled by humans or robots?

Answer 2

Neither, it’s a random occurrence that is not affected by external factors, we never know when it will happen. X-rays and CMBR are examples of this random, on-going radiation

Question 3

What’s the plum pudding model

Answer 3

The model of an atom before the current theory was found. Atom consists of spheres of positive charge with little electrons inside.

Question 4

Who disproved the plum pudding model and how

Answer 4

Rutherford devised an alpha particle scattering in which they fired alpha particles at thin gold foil. They found ‘space’ because a lot of the particles fired straight through. Some were deflected at large angles suggesting the large positive nucleus.

Question 5

In alpha radiation what change happens in the nucleus and what particles are emitted

Answer 5

2 protons and 2 neutrons are lost from the nucleus and emitted as an alpha particle

Question 6

In beta radiation what change happens in the nucleus and what particles are emitted

Answer 6

A neutron from the nucleus changes into a proton and an electron which is instantly emitted

Question 7

When the nucleus of an element emits alpha how much does the atomic and the mass number change by

Answer 7

Atomic by -2, mass by -4

Question 8

When the nucleus of an element emits beta how much does the atomic and the mass number change by

Answer 8

Atomic by +1, mass by 0

Question 9

Does gamma change the mass or atomic

Answer 9

No

Question 10

What is ionisation

Answer 10

Nuclear radiation travels through a material and knocks off the electrons from it, creating ions

Question 11

Describe alpha rays

Answer 11

Large and strongly ionising. Stopped by paper. Positive

Question 12

Describe beta rays

Answer 12

Small and fast. Less ionising, so stopped by aluminium Negative

Question 13

Describe gamma rays

Answer 13

Electromagnetic waves travel a distance so take a while to collide. Not very ionising. Stopped by lead.

Question 14

What is half-life

Answer 14

Time of the radioactive decay of a nucleus to decrease by half

Question 15

Give uses of alpha, beta and gamma rays

Answer 15

Alpha - Used in smoke alarms
Beta - Thickness monitoring
Gamma - Tracers in medicine