P7

Question 1

Which three main people discovered that atoms certain objects emit radiation ?

Answer 1

Henri bequerel , marie curie and her husband pierre

Question 2

Who carried out tests to see what stopped radiation ?

Answer 2

Ernest Rutherford

Question 3

How did Ernest Rutherford test what stopped radiation ?

Answer 3

He put different materials between the radioactive substance and a detector

Question 4

What two types pf radiation did Ernest rutherford discover ?

Answer 4

Alpha and beta particles

Question 5

What was the third radioactive particle that was discovered by scientists ?

Answer 5

Gamma radiation

Question 6

Why are substances radioactive ?

Answer 6

The atoms of radioactive substances each have a nucleus that is unstable .

Question 7

How does an unstable nucleas become stable ?

Answer 7

By emitting alpha , beta or gamma radiation

Question 8

When an unstable nucleas emits radiation , what is this described as ?

Answer 8

Decaying

Question 9

How can a nucleus be unstable ?

Answer 9

For example carbon -14 is an isotope of carbon which is unstable . It has two extra neutrons compared to the stable carbon 12.

Question 10

What two things can radiation be in the form of ?

Answer 10

A high energy particle or a wave

Question 11

The process of emitting radiation is called what ?

Answer 11

Radioactive decay

Question 12

What is a common way of detecting radiation ?

Answer 12

The Geiger-Muller Tube is connected to a Geiger counter . This is a common way of detecting radiation and measuring a count rate .

Question 13

What was the first observation made from Rutherfords gold foil experiment ?

Answer 13

Most alpha particles travel through the foil undeflected

Question 14

What was the second observation made from Rutherford’s gold foil experiment ?

Answer 14

Some alpha particles are deflected at angles .

Question 15

What did the first observation of the gold foil experiment mean ?

Answer 15

That there is space between the atom

Question 16

What did observation 2 mean in the gold foil experiment ?

Answer 16

This must of meant that there are positive sub atomic particles within the atom . A proton in the middle that deflected the alpha particles .

Question 17

What was observation 3 in the gold foil experiment ?

Answer 17

Occasionally , an alpha particle travel back from the foil

Question 18

What does observation 3 mean in the gold foil experiment ?

Answer 18

This meant that it hit something dense in the nucleas

Question 19

What did Rutherfords gold foil experiment show ?

Answer 19

That there was a small positively charged central nucleus where most of the atoms mass is located .

Question 20

What is the symbol for alpha particles ?

Answer 20

A

Question 21

What is an alpha particle the same as and why ?

Answer 21

The same as helium nucleus , this is because they consist of two neutrons and two protons.

Question 22

What charge does an alpha particle have ?

Answer 22

They have a charge of +2

Question 23

What is an alpha particle stopped by ?

Answer 23

Paper

Question 24

What is the symbol for a beta particle ?

Answer 24

B

Question 25

What is a beta particle ?

Answer 25

A fast moving electron

Question 26

What charge does a beta particle have ?

Answer 26

-1

Question 27

What is a beta particle stopped by ?

Answer 27

Aluminium

Question 28

What is the symbol for a gamma ray ?

Answer 28

Y

Question 29

What is a gamma ray ?

Answer 29

An electromagnetic wave

Question 30

What charge does a gamma ray have ?

Answer 30

It has no charge

Question 31

What is a gamma ray stopped by ?

Answer 31

A few mm of lead

Question 32

What happens when an atom is ionised ?

Answer 32

The number of electrons it has changes

Question 33

When an unstable nucleus emits an alpha particle what happens to its atomic and mass number ?

Answer 33

Its atomic number goes down by 2 and its mass number goes down by 4 . The mass and charge of the nucleus are both reduced .

Question 34

What is a count rate ?

Answer 34

The number of decays recorded each second by a detector

Question 35

Is radioactive decay a random process ?

Answer 35

Yes

Question 36

What is a half life ?

Answer 36

The time it takes for the number of nuclei of a sample of radioactive isotopes to decrease by half

Question 37

Give an example of a half life .

Answer 37

Uranium-235 has a half life of 704 million years . This means it would take 704 million years for the activity of a uranium-235 sample to decrease to half its original amount .

Question 38

How do you calculate half life ?

Answer 38

1. Measure the initial activity of the sample 2. Determine the half life of this original activity. 3. Measure how the activity changes with time

Question 39

What is an alpha particles range in air ?

Answer 39

5 cm

Question 40

What is a beta particles range in air ?

Answer 40

1 metre

Question 41

What is a gamma particles range in air?

Answer 41

Unlimited

Question 42

What is the range in air ?

Answer 42

Distance before they collide with air particles .

Question 43

What is the ionising ability from strongest to weakest in terms of alpha , beta and gamma radiation ?

Answer 43

1. Alpha 2. Beta 3. Gamma

Question 45

What is ionisation ?

Answer 45

The ability for nuclear radiation to remove electrons from atoms to form ions .

Question 46

What is the activity of a radioactive source ?

Answer 46

The number of unstable nuclei that decay every second .

Question 47

What is contamination defined as ?

Answer 47

The unwanted presence of materials containing radioactive atoms on other materials .

Question 48

What is irradiation ?

Answer 48

The process of exposing a material to alpha, beta or gamma radiation

Question 49

How can we protect our selves from radiation ?

Answer 49

Radiation suit and lead clothing