Radioactivity

Question 1

What did John dalton think matter was made up of

Answer 1

Tiny spheres

Question 2

Who discovered the plum pudding model

Answer 2

JJ Thompson

Question 3

What experiment proved the plum pudding wrong

Answer 3

Alpha scattering experiment

Question 4

What conclusions were made from the alpha scattering experiment

Answer 4

Most of the atom is empty space
The mass of the atom is concentrated in the centre
The nucleus has a positive charge

Question 5

What is tha alpha scattering experiment

Answer 5

Scientist in Rutherford lab fires a beam of alpha particles at a thin gold foil

Question 6

What were the predictions of the alpha particles experiment and what happened

Answer 6

Due to the plum pudding model it was expected that atom would pass through while most did some were deflected back and some were slightly deflected

Question 7

Why did they conclude the nucleus was positive in the alpha particle experiment

Answer 7

Because the nucleus repelled the positive charge on the Gould sheet

Question 8

Who proved the existence of neutrons

Answer 8

James. Chadwick

Question 9

Describe the process of radioactive decay

Answer 9

Unstable isotopes decay into other elements and give out radiation as they try to become more stable they try to balance the number of protons and neutrons in the nucleus

Question 10

What is alpha radiation

Answer 10

Find an alpha particle is emitted from the nucleus

Question 11

Properties of an alpha particle

Answer 11

Alpha particles are consist of two neutrons and two protons they don’t penetrate very far into materials and Can be stopped quickly they can only travel a few centimetres in air and can be absorbed by a sheet of paper however they are strongly ionising

Question 12

Properties of a beta particle

Answer 12

They have no mass and charge of minus one they are moderately ionising penetrate moderately far into materials and have range in air of a few metres

Question 13

What is beta radiation

Answer 13

It is A fast-moving electron released by the nucleus for every beta particle emitted a neutron in the nucleus has turned into a proton

Question 14

What are gamma rays

Answer 14

Waves of electromagnetic radiation released by the nucleus

Question 15

Properties of gamma rays

Answer 15

Penetrate far into materials without being stopped and travel long distances three at the weekly ionising as they tend to pass through atoms rather than colliding with them they can be absorbed by six sheets of lads on metres of conch Street

Question 16

What is the use of ionising radiation (alpha particles ) in smoke detectors not a threat to peoples house

Answer 16

4:30 do not travel far in air so they can be stopped by thin sheet of material therefore they cannot escape the smoke detector and harm people

Question 17

If the atomic number of an isotope is Lower does that mean the charge is the same

Answer 17

No the charge will be lower as the number of protons in the nucleus is fewer

Question 18

An unstable isotope is put inside a pipe which has a leak and radiation detectors moved along the path of a pipe explain how this method would help identify the leak

Answer 18

The unstable isotope for travel along the pipe add would be blocked by the pipe unless there is a leak therefore where there is a leak the radiation detector would have a higher current rate as the isotopes of radiation has escaped the pipe the radiation should be get a gamma rate as gamma rays are able to escape the pipe and reach the detector

Question 19

What happens to an element when it goes through alpha decay

Answer 19

The atomic mass reduces by four and the atomic number reduces by two.

Question 20

What happened to the element when it goes through beta decay

Answer 20

The atomic mass stays the same and the atomic number increases by one

Question 21

What can radiation be measured with

Answer 21

A Geiger-Müller tube and counter

Question 22

What is the count rate

Answer 22

The number of decays recorded each second

Question 23

What is half life

Answer 23

The time taken for the number of radioactive nuclei in an isotope to halve

Question 24

What can half life help to do

Answer 24

Find the rate at which a source decay and find its activity

Question 25

What does radioactivity do over time

Answer 25

It decreases

Question 26

Why can we not measure the activity

Answer 26

Because the activity never reaches zero

Question 27

What is the term for exposure to radiation

Answer 27

Irradiation

Question 28

How can we limit irradiation

Answer 28

By putting sources in lead lined boxes and standing behind a barrier when using the substance

Question 29

Which radiation is the most dangerous outside your body and why

Answer 29

Beta and gamma sources because they can penetrate the body and get to delicate organs

Question 30

What is the difference between contamination and irradiation

Answer 30

Irradiation is when an object is exposed to radiation however contamination is when unwanted radiation particles get onto objects

Question 31

Should someone who is handling alpha particles be concerned about irradiation or contamination

Answer 31

Contamination as alpha particles cannot penetrate through skin so irradiation will not be a problem however if the other particles are ingested Or breathed in then they can be very dangerous as it can contaminate vital organs this is because they are strongly ionising