Chapter 7 Radioactivity

Question 1

How was radioactive materials discovered

Answer 1

Henri becquerel used covered photographic plates that were placed under uranium salts to discover radioactivity.

Henri becquereles work was expanded on by marie & pierre curie, who investigated amd discovered a large range of new radio active elements.

Question 2

What is radiation

Answer 2

The emmision of energy as electromagnetic waves or as moving subatomic particles

Question 3

What are the main three different types of radiation

Answer 3

Beta,alpha,gamma

Question 4

What is radioactivity

Answer 4

Process by which an unstable atomic nucleus looses energy by radiation

Question 5

What occurs when an unstable nucleus decays

Answer 5

It emits radiation

Question 6

What is background radiation

Answer 6

the natrual radiation that’s always present in the envriomment

Question 7

3 sources of background radiation

Answer 7

Cosmic radiation,terrestial radiation,rocks and soil

Question 8

What is a geiger counter

Answer 8

instruments that detect and measure ionizing radiation, as emitted by radioactive sources

Question 9

What is the plum pudding model and who mad it in what year

Answer 9

After the discovery of the electron as being a subatomic particle in atoms, J. J.
Thomson came up with the Plum Pudding Model of the atom in 1904.
Electrons buried inside the atom which is made up of positively charged material

Question 10

In the plum pudding:
What does the dough represent?
What does the plums represent?
How’s it different to todays model?

Answer 10

Cloud of positive charge
Electrons
Electrons inside nucelus whereas now they are in shells

Question 11

3 observation and interprataions from rutherfords gold foil experiement

Answer 11

Most alpha particles traveled through the foil undeflected - Lot’s of empty space in an atom

Some alpha particles are deflected by small angles - As alpha particles are positvely charged it repelled the positvely charged nucleus

Occasionally, an alpha particle travels back from the foil - Alpha particles must have collided with someone dense in the centre,nucelus carrys most atomic mass in an atom

Question 12

What is an isotope

Answer 12

An atom with a different number of neutrons

Question 13

What is a radioisotope(example)

Answer 13

An isotope which is radioactive (carbon 14)

Question 14

What is alpha radiation

Answer 14

The nucleus of a helium atom travelling at extremely high speed

Question 15

Alpha decay math/equation

Answer 15

A X —— > A-4 D + 4 a
Z Z-2 2

Question 16

What is beta radiation

Answer 16

The fast moving high energy electron not on an shell

Question 17

Beta maths/equation

Answer 17

A X —— > A D + 0 B
Z Z+1 -1

Question 18

What is gamma radiation

Answer 18

Part of EM spectrum; it’s a wave with very high freqeuncy a very short wavelength

Question 19

Gamma maths/equation

Answer 19

Dosen’t change anything, needs alpha or beta with it to change

Question 20

Fill in gaps- Radioactivity is measured in units of ________, where 1 unit is equal to one _________ per second.

Answer 20

Becquerels
Decay event

Question 21

Fill in gaps - Nuclear radiation is the emission of ______ from the nucleus in the form of _______ particles or ___________ waves.

Answer 21

Energy,subatomic,electromagnetic

Question 22

Fill in gaps - Unstable _______ decay ________ by the emission of _____, beta, or ______ radiation.

Answer 22

Nuclei,randomly,alpha,gamma

Question 23

Alphas range in air,stopped by,ionsing ability

Answer 23

5cm
Piece of paper
Very strong ionising

Question 24

Betas range in air,stopped by,ionsing ability

Answer 24

1m
Few mm of aluminium
Quite strong ionising

Question 25

Gammas range in air,stopped by,ionsing ability

Answer 25

Unlimited
Several cm of lead or 1m of concrete
Weak ionising

Question 26

What is ionsing power

Answer 26

Ionising power is the ability for nuclear radiation to remove electrons from atoms to form ions.

Question 27

Why is ionsing radiation dangerous

Answer 27

has enough energy to remove electrons from atom

So it has the ability to change the chemical composition of the material it interacts with.

In living tissue this effect can result in a process that damages DNA and can result in the death or mutation (cancer) of the impacted cell.