Nuclear Decay and Radiation 1.3

Question 1

Nuclear Decay

Answer 1

A nucleus is a cluster of protons and neutrons in the centre of an atom, surrounded by a cloud of electrons. However, the protons and neutrons inside the nucleus are constantly moving, vibrating, rotating and rearranging, causing some to emit electromagnetic radiation called gamma rays. Sometimes, nuclei even eject particles at high speed. This emission of electromagnetic radiation or particles is known as a nuclear reaction or nuclear decay.

During nuclear decay, atoms might change from one element to another. This change to another element is known as transmutation. Transmutation never occurs during everyday chemical reactions such as those that happen when you breathe, bake a cake or burn paper, but only during nuclear decay.

Question 2

Radioisotopes

Answer 2

Most of the atoms which make up everything around us contain stable nuclei. This means that the nuclei will never undergo nuclear decay. However, a tiny fraction of atoms has unstable nuclei. These unstable atoms could eject particles or electromagnetic waves fro, their nucleus at any moment and undergo nuclear decay. These unstable atoms are known as radioisotopes.

Each type of atom may have several isotopes but only some isotopes are radioactive. Isotopes are atoms that have the same number of protons but a different number of neutrons. For example, carbon has three naturally occurring isotopes called carbon-12, carbon-13 and carbon-14.

Question 3

Alpha Radiation

Answer 3

Alpha particles are large, heavy ad slow compared to beta particles and gamma rays, which makes them 20 times better and ionising molecules. However, their large size also means that alpha radiation can only travel a few centimetres in air and is easily blocked by a thin sheet of paper or even a layer of dead skin. This means that alpha radiation can be handled relatively safely. However, if isotopes emitting alpha radiation get inside the body, the effects can be fatal. Radioactive gases which emit alpha radiation are particularly dangerous inside the lung.

Question 4

Beta Radiation

Answer 4

Beta particles which make up beta radiation are small and fast which means that beta radiation penetrates the skin deeper than alpha radiation. This means beta radiation is more likely to cause radiation burns to the skin and eyes. However, beta radiation can be stopped by as much as a thin sheet of aluminium.

Question 5

Gamma Radiation

Answer 5

Gamma radiation can travel through skin, bone and aluminium, making it extremely dangerous to humans, and difficult to block. Only a thick layer of concrete or lead will block the radiation. This is because gamma radiation is made up of electromagnetic waves rather than particles. This means that gamma rays don’t have any mass or charge and travel at the speed of light. Other forms of electromagnetic waves include radio waves, microwaves, visible light, ultraviolet light and x-rays. However, only gamma rays, x-rays and certain types of ultraviolet light are powerful enough to ionise molecules and cause cell damage.

Question 6

Medical and Industrial Radiation

Answer 6

While radiation should be handled with care, there are also many benefits from it if used correctly.

Question 7

Fusion and Fission Reactions

Answer 7

In a fission reaction, a large nucleus splits into two almost equally sized pieces, in a fusion reaction, two smaller nuclei come together forming a larger nucleus. In both cases, the reactions release huge amounts of energy which can be both useful or destructive.