Atomic Structure And Radioactivity

Question 1

What is radioactive decay?

Answer 1

Some isotopes have unstable nuclei and to become stable the nucleus gives out radiation. It is completely random process

Question 2

What is an isotope?

Answer 2

An element that has different numbers of neutrons to the original.

Question 3

What is the “activity” in terms of decay

Answer 3

the rate at which a source of unstable nuclei decay.

Question 4

what is the units for activity/ nuclei decay

Answer 4

Becquerel (Bq)
1 Bq = 1 decay per second

Question 5

What piece of equipment is used to measure the activity of a radioactive source?

Answer 5

Geiger - Muller tube

Question 6

What is count rate in terms of decay?

Answer 6

The number of decays recorded each second by a detector

Question 7

What is the alpha particle structure

Answer 7

2 protons and 2 neutron
Aka the same as the nucleus of a helium atom

Question 8

What is the structure of a beta particle?

Answer 8

1 electron

Question 9

What is a beta particle?

Answer 9

An electron which is ejected from a nucleus at a very high speed.

Question 10

How is a beta particle formed

Answer 10

When a neutron changes into a proton and electron and the electron is ejected

Question 11

Is a gamma ray a particle?

Answer 11

NO

Question 12

Which type of radiation is a type of electromagnetic radiation from the nucleus

Answer 12

Gamma Rays

Question 13

Alpha particle range in air

Answer 13

Alpha particles are large and can travel 5 cm in the air before stopping as they collide with the air particles

Question 14

Beta particles range in air?

Answer 14

Can travel around 15cm before stopping

Question 15

Gamma radiation range in air

Answer 15

Can travel a couple of metres before stopping

Question 16

What is the barrier that stops alpha particles and what does this mean about their penetrating power?

Answer 16

A single piece of paper
Alpha particles have weak penetrating power

Question 17

What barrier can stop beta particles and what does this mean about their penetrating forces?

Answer 17

A few centimetres of aluminium
This means it has stronger penetrating forces

Question 18

What is the barrier that can stop gamma radiation and what does this mean about its penetrating power?

Answer 18

Several centimetres of lead
Has very strong penetrating power

Question 19

What is a ionising power?

Answer 19

When radiation collides with atoms, that can cause the atoms to lose electrons from ions

Question 20

What are the three radiations ionising power?

Answer 20

Alpha - very strong
Beta - quite strong
Gamma - weak

Question 21

What are the two examples of large unstable nuclei?

Answer 21

Plutonium + Uranium (certain isotopes)

Question 22

What happens in nuclear fission

Answer 22

A large and unstable nucleus splits
Can happen spontaneously but quite rare
normally for fission to take place the nucleus has to absorb a neutron. This causes the element to split and form two smaller nuclei (daughter) which are mostly even in size. It also emits 2 or 3 neutrons and gamma radiation. The neutrons that are released can create more fission after wards. This releases lots of energy.

Question 23

What type of energy do all fission reaction products have?

Answer 23

Kinetic energy

Question 24

What type of reaction is a cycle of fission

Answer 24

Chain reaction

Question 25

Where is controlled and uncontrolled fission found and what does it create

Answer 25

Controlled is Found in nuclear reactors and is used to create energy
Uncontrolled fission reactions are found with bombs

Question 26

What happens in nuclear fusion?

Answer 26

Two light nuclei (hydrogen) are joined to form a heavier nucleus. Some of the mass of the nuclei can be converted into energy, which is released as radiation.

Question 27

Is nuclear fusion a chain reaction

Answer 27

No

Question 28

What are the two definitions of a half life of a radioactive isotope

Answer 28

• The time it takes for the number of nuclei of the isotope sample to halve
• the time it takes or the count rate/ activity from a sample containing the isotope to fall to half its initial level