Radioactivity

Question 1

What is the symbol for:

1. A symbol of an element
2. The mass number
3. Atomic number

Answer 1

1. X
2. A
3. Z

Question 2

What is:

Radioactive decay?

Answer 2

The spontaneous transformation of an unstable nucleus into a more stable one by the release of radiation. It is a random process which means that one cannot know what nucleus will decay or when it will decay becuase it is down to chance

Question 3

What are the different:

Decay processes?
Why do they occur?

Answer 3

• Alpha - too heavy nucleus
• Beta - the atom is too unstable
• Gamma - there is an excess of energy
• Neutron radiation - (not done yet)

Question 4

Characteristics of:

Alpha radiation

Answer 4

• Happens when an atom has a too heavy nucleus
• Highly ionising
• Weak penetrating leading to it travelling very small distances, and is stopped by a sheet of paper
• emmits a Helium nucleus
• Equation: ZAX -> (X-4a -2Z) + a

Question 5

Characteristics of:

Beta radiation

Answer 5

• Happens when an atom is too far away from the line of stability
• A neutron is turned into a proton and emits a beta particle (electron)
• Moderately ionising and moderately penetrating, and are stopped by a sheet of aluminum
• Equation: ZAX -> (X A Z+1) + e-

Question 6

Characteristics of:

Gamma radiation

Answer 6

• A wave that contains energy but no mass
• Lowly ionising and highly penetrating
• Stopped by many centimetres of lead
• Released when there is excess energy

Question 6

What:

Holds the nucleus together

Answer 6

Strong nuclear force for nucleons, which acts on very small distances

Question 6

Why is it impossible to:

Predict radioactive decay?

Answer 6

Because it is a random process

Question 7

Why do atoms:

Go through radioactive decay

Answer 7

To become more stable as the atomic number and therefore element will change

Question 8

What are the different:

Sources of background radiation

Answer 8

50 percent radon gas
14 gamma rays from the ground
10 cosmic rays
12 food
12 medical
1 other

Question 9

What is:

A half life

Answer 9

The time it takes for half of the nuclei of unstable atoms to undergo radioactive decay

Question 10

Applications of:

Radioactivity

Answer 10

Alarms, cancer treatment, measuring thickness and imaging

Question 11

LEARN SYMBOLS BETA GAMMA ALPHA

Question 12

What is:

irradiation

Answer 12

When an object or person is exposed to radiation

Question 14

What is:

Contamination

Question 15

What is:

Contamination

Answer 15

When a radioactive source is in contact with an object of person. The radioactive substance rather than the emissions are present. THe object remains radioactive until the contamination is removed or decays naturally.