P4 Atomic Structure

Question 1

What are the 3 types of radiation?

Answer 1

Alpha, beta, gamma

Question 2

What does an alpha particle consist of?

Answer 2

2 protons, 2 neutrons

Question 3

What does a beta particle consist of?

Answer 3

An electron

Question 4

What does gamma radiation consist of?

Answer 4

Waves

Question 5

What is the charge of alpha radiation?

Answer 5

+2

Question 6

What is the charge of beta radiation?

Answer 6

-1

Question 7

What is the charge of gamma radiation?

Answer 7

0

Question 8

What is the range in air of alpha radiation?

Answer 8

A few cm

Question 9

What is the range in air of beta radiation?

Answer 9

A few m

Question 10

What is the range in air of gamma radiation?

Answer 10

Kilometres

Question 11

What is alpha radiation absorbed by?

Answer 11

Paper

Question 12

What is beta radiation absorbed by?

Answer 12

A few cm Aluminium

Question 13

What is gamma radiation absorbed by?

Answer 13

A few cm Lead OR metres of concrete

Question 14

What is the ionising power of alpha radiation?

Answer 14

High

Question 15

What is the ionising power of beta radiation?

Answer 15

Medium

Question 16

What is the ionising power of gamma radiation?

Answer 16

Low

Question 17

Name 3 safety precautions to take when handling radioactive sources:

Answer 17

1. Keep tool in a lead box to stop gamma spreading
2. Sources handled at arm’s length and pointed at ground
3. Audience stands back - greater distance, less exposure

Question 18

What is ionising radiation?

Answer 18

Radiation which can ‘knock’ electrons off of atoms which is what makes it dangerous

Question 19

Give 3 uses of radiation?

Answer 19

1. Target cells to treat tumours
2. Radioactive tracer
3. Automatic thickness monitoring (beta particles)

Question 20

What are gamma rays?

Answer 20

Very high frequency electromagnetic waves

Question 21

When are gamma rays produced?

Answer 21

When an unstable nucleus loses energy

Question 22

What is the greek letter for gamma radiation?

Answer 22

ɣ

Question 23

What is a beta particle?

Answer 23

A high speed electron

Question 24

Where do beta particles come from?

Answer 24

A nucleus where a neutron has decayed into an electron and a proton

Question 25

What is the greek letter for beta radiation?

Answer 25

β

Question 26

What is an alpha parrticle?

Answer 26

The same as a Helium nucleus - 2 protons, 2 neutrons

Question 27

What is the greek letter for alpha radiation?

Answer 27

α

Question 28

What is radioactivity?

Answer 28

Radioactive atoms with unstable nuclei

Question 29

Why do unstable nuclei decay?

Answer 29

To become more stable - emits radiation

Question 30

How do you predict radioactive decay?

Answer 30

You can't - it is a random event

Question 31

What is the count rate?

Answer 31

The number of decays recorded each second by a detector (eg.a Geiger-Muller Tube)

Question 32

What is the activity?

Answer 32

The rate at which a stable nuclei decays

Question 33

What are activity and count rate measured in?

Answer 33

Becquerels

Question 34

What is the equation for count rate?

Answer 34

No. of emissions / Time (s) - background radiation

Question 35

What is the half-life?

Answer 35

The time it takes for the number of nuclei in a sample to halve OR for the count rate for an isotope in a sample to fall to 1/2 its initial value

Question 36

Who first talked about atoms in 440 BC?

Answer 36

Democritus

Question 37

What does 'atom' mean in Greek?

Answer 37

No cut

Question 38

What did John Dalton say in 1800s?

Answer 38

Different elements have different atoms. Imagined these as indivisible spheres

Question 39

What did J.J. Thompson say in 1898?

Answer 39

Discovered electrons. Developed Plum Pudding Model - electrons randomly embedded in a ball of positive charge

Question 40

Who developed the Plum Pudding Model?

Answer 40

J.J. Thompson

Question 41

What did Rutherford say in 1908?

Answer 41

Alpha scattering - fired alpha particles at gold foil to discover nucleus.

Question 42

Who developed the nuclear model?

Answer 42

Earnest Rutherford

Question 43

What did Neils Bohr say in 1913?

Answer 43

Electrons found in shells and charge concentrated in centre of atom

Question 44

What did James Chadwick say in 1939?

Answer 44

Discovered the neutron and added to the nucleus

Question 45

What is nuclear fission?

Answer 45

Splitting a nucleus (often Uranium) into 2 or more daughter nuclei and 2 - 3 neutrons moving at high speeds - energy released as gamma waves

Question 46

What is nuclear fusion?

Answer 46

Forming of 2 smaller atomic nuclei to form a larger one. Some mass converted into energy.

Question 47

Give an example of alpha decay:

Answer 47

238 92 U --> 234 90 Th + 4 2 α

Question 48

How is alpha decay calculated:

Answer 48

4 from mass number, 2 from atomic number (4 from top, 2 from base)

Question 49

Give an example of beta decay:

Answer 49

14 6 C --> 14 7 N + 0 -1 β

Question 50

How is beta decay calculated:

Answer 50

Mass number stays same, add 1 to atomic number (Add one to base, top stays same)

Question 51

What happens in beta decay?

Answer 51

A neutron turns into a proton (too many neutrons in a nucleus). Proton comes with a +1 charge. Also forms a -1 electron to balance charge. Electron booted out of the nucleus as can't stay there (electrons orbit in shells)