Radioactivity Part 1

Question 1

Define atom

Answer 1

Smallest unit of matter that still retains the chemical properties of its element

Question 2

Describe the structure of the atom.

Answer 2

The atom consists of a central positive nucleus containing protons and neutrons, with negative electrons orbiting gin shells around the nucleus.

Question 3

Describe the Rutherford model.

Answer 3

Alpha particles were fired at a thin gold leaf.
About 1 in 8000 would strike the nucleus and be deflected.
Far from the gold nucleus the alpha particles experience little or no force and continue in a straight path, some are deflected by a small amount and very rarely, alpha particles were completely turned around.

Question 4

Define isotope

Answer 4

Atoms that have the same number of protons but a different number of neutrons.

Question 5

Describe nuclear fission.

Answer 5

Fission occurs when a heavy nucleus divides into two smaller ones.
This is induced by introduction of a neutron.
A neutron has no charge and therefore not deflected by the positively charged protons in the nucleus.
U-235 and Pu-239 are two known fissile materials.

Question 6

Describe a chain reaction.

Answer 6

In a critical reaction enough fissile material is brought together to produce a sustained fission or chain reaction.

Question 7

How can a fission chain reaction be controlled?

Answer 7

The energy can be harnessed to produce electricity. Fission can be controlled by separating the fissile material and placing control rods between the sections. The control rods absorb some of the neutrons therefore slowing down the reaction.

Question 8

Describe how a nuclear power station works to produce electricity.

Answer 8

Heat from the control rods are used to produce steam, which is used to turn the turbine generators which produce electricity.

Question 9

Describe nuclear fusion.

Answer 9

Two nuclei with low mass numbers combine to produce a single nucleus with a higher mass number.