Nuclear decay

Question 1

Mass defect / mass deficit

Answer 1

The difference when measuring the mass of a nucleus and the mass of of its constituents, (mass of the nucleus is always lower)

Question 2

The “mass” that is lost…

Answer 2

is converted into energy and released when nucleons fuse to form a nucleus

Question 3

Binding energy

Answer 3

the energy required to separate the nucleus into its constituents

Question 4

Nuclear fission

Answer 4

the splitting of a large nucleus into two daughter nuclei. Energy is released during fission because the smaller daughter nuclei have a higher binding energy per nucleon

Question 5

Nuclear fusion

Answer 5

where two smaller nuclei join together to form one larger nucleus. It only occurs in fairly small nuclei. Energy is released during fusion becase the larger nucleus has a much higher binding energy per nucleon.

Question 6

Sources of background radiation

Answer 6

• Radon gas –> released from rocks
• Artificial sources –> caused by nuclear weapons testing and nuclear meltdowns
• Cosmic rays –> enter the Earth’s atmosphere from space
• Rocks –> naturaly ocurring radioactive isotopes

Question 7

Differing penetrating powers experiment

Answer 7

1. Using a GM tube and counter fin the background count when the source isn’t present
2. Place the source of radiation close to the GM tube and measure the count rate
3. Place a sheet of paper between the source and GM tube and measure count rate again, if the count rate decreases significantly, then the source is emitting alpha radiaton
4. Repeat the above step using aluminium foil and several inches of lead. If there is a significant decrease in count rate for aluminium then beta radiation is being emittes and with lead gamma radiation

Question 8

Decay constant

Answer 8

probability of a nucleus decaying per unit time

Question 9

half-life

Answer 9

time taken for the number of nuclei to halve

Question 10

activity

Answer 10

the number of nuclei that decay per second