P4 Atomic Structure

Question 1

Give an approximation for the radius of an atom

Answer 1

1x10^-10 metres

Question 2

What are the three subatomic constituents of an atom?

Answer 2

Proton
Neutron
Electron

Question 3

Where is the most of the mass of an atom concentrated?

Answer 3

In the nucleus

Question 4

Approximately what proportion of the total radius of an atom is the radius of the nucleus?

Answer 4

1/10,000

Question 5

Describe the arrangement of protons, neutrons and electrons in an atom

Answer 5

The protons and neutrons are found in the atoms nucleus
The electrons are found in discrete energy levels around the nucleus

Question 6

What type of charge does the nucleus of an atom have? Why?

Answer 6

Positive charge
The nucleus contains protons and neutrons
Protons have a positive charge
Neutrons have no charge

Question 7

Give two ways that an atoms electron arrangement can be changed

Answer 7

Absorbing electromagnetic radiation
Emitting electromagnetic radiation

Question 8

Explain how an atoms electron arrangement changes when it absorbs electromagnetic radiation

Answer 8

Electrons move further away from the nucleus
They move to a higher energy level

Question 9

Explain how an atoms electron arrangement changes when it emits electromagnetic radiation

Answer 9

Electrons move closer to the nucleus
The move to a lower energy level

Question 10

What are the three types of radiation?

Answer 10

Alpha
Beta
Gamma

Question 11

What is the charge of alpha radiation

Answer 11

2+

Question 12

What is the charge of beta radiation

Answer 12

1-

Question 13

What is the charge of gamma radiation

Answer 13

No charge

Question 14

What is radiation

Answer 14

Radiation is either particles or waves emitted by an unstable nucleus which carry energy away from the nucleus to make it more stable

Question 15

What has the most penetrating power?

Answer 15

Gamma
Lead stops it

Question 16

What is the most ionising

Answer 16

Alpha particles are the most ionising as they have the greatest charge

Question 17

What is the least ionising

Answer 17

Gamma radiation is the least ionising because it has no charge

Question 18

Define ionising

Answer 18

Ability for an atom to lose an electron

Question 19

What is background radiation

Answer 19

Background radiation is ionising radiation from radioactive sources in the environment

Question 20

What is an example of natural source background radiation

Answer 20

Rocks
Food
Cosmic rays

Question 21

What are examples of man made background radiation

Answer 21

Medical sources
Nuclear power plant

Question 22

What is the plum pudding model

Answer 22

Solid ball of positive charge
It contained negative electrons within the positive solid

Question 23

What is the change in the nucleus of alpha decay

Answer 23

Loses two protons and two neutrons

Question 24

What is the change in the nucleus of beta decay

Answer 24

Neutron goes to proton then electron is emitted

Question 25

What is half life

Answer 25

The half life is the time taken for the number of radioactive nuclei in an isotope to half. This can take hours, weeks, years

Question 26

What is the half life equation

Answer 26

Count rate (number of unstable nuclei after n half lives) = initial count rate (number of unstable nuclei)/ —————————————————— 2^n

Question 27

Define irradiation

Answer 27

Irradiation is when a surface is exposed to radiation. An example is X-rays, sterilising fruit

Question 28

Define contamination

Answer 28

Contamination is when an object is mixed with a radioactive substance. An example is water pipe leaks