The nucleus, radioactivity & radiation

Question 1

What is the definition of radiation?

Answer 1

Energy in motion, either as a particle or an electromagnetic wave causing ionization.

Question 2

How can the radiation emitted by a radioactive substance be detected?

Answer 2

By it’s ionising effects

Question 3

List the three types of radiation

Answer 3

• Alpha
• Betta
• Gamma

Question 4

The thicker the substance, the harder it is for the (a) and (b) particles to get through.

Answer 4

a. Alpha

b. Betta

Question 5

What are the principles of a spark detector?

Answer 5

It detects the sparks that jump where the particles pass between radioactive sources in the air and the gauze, therefore ionising.

Question 6

What are the principles of a Geiger-Müller tube?

Answer 6

It is connected to a counting circuit and counts how many ionising particles enter it.

Question 7

What are the principles of an ionisation chamber?

Answer 7

When a charged particle enters the chamber, it converts some of the gas molecules to positive ions.

Question 8

How does alpha radiation compare to gamma radiation?

Answer 8

Gamma has no charge, whereas Alpha is positive.
Gamma is mass less, whereas Alpha has a large mass.
Gamma is weak in ionisation, whereas Alpha is highly ionising.
Gamma is the most penetrating, whereas Alpha is least penetrating.

Question 9

What is the ionising ability/penetration of beta radiation?

Answer 9

Beta is fairly ionising and penetrates air & paper.

Question 10

What effect does alpha radiation have on a photographic plate?

Answer 10

The more radioactive it is, the darker and the foggier the plate will become

Question 11

Explain deflection in electric and magnetic fields:

Answer 11

With Alpha, it is only slightly deflected in magnetic fields but fully deflected in electric fields. With Beta it is fully deflected in both fields and in Gamma it is completely undeflected

Question 12

12) Describe the Geiger-Marsden experiment:

Answer 12

it’s a series of experiments proving that every atom contains a nucleus where it is positively charged and most of it’s mass is concentrated.

Question 13

13) Explain Rutherford’s nuclear model interpretation:

Answer 13

It is a simple version of the atom model—>

Question 14

14) Describe the protons, neutrons and electrons in a simple nuclear model:

Answer 14

Protons + Neutrons are in the nucleus and the electrons orbit around it.

Question 15

15) What is an atomic number?

Answer 15

The atomic number is the proton number, therefore the total positive charge in the
atomic nucleus.

Question 16

16) What is a nucleon number?

Answer 16

The mass number (A) or nucleon number, is the total number of protons and neutrons in
an atom.

Question 17

17) What is the Z number?

Answer 17

The proton number

Question 18

18) What is the definition of “isotopes”?

Answer 18

An isotope is of the same element, containing equal numbers of protons but different nucleon numbers.

Question 19

19) What are some examples of isotopes?

Answer 19

Carbon12, Carbon13 and Carbon14

Question 20

20) What is the definition of “half-life”?

Answer 20

Half-life is the time it takes for the activity or to count to reduce itself by 50%.

Question 21

22) Describe an experiment from which a radioactive decay curve can be obtained?

Answer 21

Using a Geiger counter to measure the radiation in various objects, obtaining both beats per hour and time.

Question 22

23) Why is radioactivity a random process?

Answer 22

Due to nuclear instability and independent of external conditions.

Question 23

24) For what reason would you need to take off two from all of your half-life results?

Answer 23

Due to natural sources of background radiation

Question 24

25) Recall some uses of radioactive isotopes in medical & non-medical situations?

Answer 24

• X-rays
• To kill cancerous cells
• Fertilisers
• Insect Control
• Smoke Detectors
• Therapy

Question 25

26) Recall sWhat are the hazards associated with radioactivity?

Answer 25

Use the effects of distance, shielding and reducing exposure time