What is proton number?
Proton number, Z, is also known as the atomic number, represents the number of protons of an element
What is nucleon number?
Nucleon number, A, is also known as mass number, is the total number of neutrons and protons in the nucleus of an atom
What are isotopes?
Isotopes are atoms of the same element that have the same number of protons but different number of neutrons
What is impossible to measure relating to radioactivity?
- make the radioactive nucleus emit radiation by heating, cooling, or any other methods.
- predict when radioactive nucleus will emit radiation.
- know the direction in which emitted radiation will leave a nucleus
What is radioactive decay?
It is a random and spontaneous process by which an unstable atomic nucleus loses its energy by emission of electromagnetic radiation or particle(s).
What is an alpha particle?
An alpha particle consists of two protons and two neutrons tightly bounded together.
What is a beta particle?
A beta particle is a fast-moving electron ejected from a radioactive nucleus.
What is a gamma ray?
An gamma ray is electromagnetic radiation emitted by a radioactive nucleus with excess energy
What happens to atom during alpha decay?
- nucleus emits an α-particle (identical to helium nucleus
- nucleon number decreases by 4 and proton number decreases by 2
For example: radium emits an α-particle, decays to radon
What happens to atom during beta decay?
- nucleus emits an β-particle (an electron)
- nucleon number remains the same and proton number increases by 1
For example: carbon-14 emits a β-particle, decays to nitrogen
State ionising effect from highest to lowest.
alpha particles, beta particles, gamma rays
State penetrating ability of alpha particle
- Least
- Easily absorbed by a piece of paper, a thin aluminium foil or human skin
State penetrating ability of beta particle
- Medium
- Absorbed by a piece of aluminium foil that is a few millimetres thick
State penetrating ability of gamma ray
- Highest
- Passes through most materials easily but absorbed by lead that is a few centimetres thick or very thick concrete
State artificial and natural sources of background radiation
Artificial
- Medical X-Rays
- Building Materials
- Waste products from nuclear power plants
Natural
- Rocks
- Radon gas in the air
- Food and drink (food high in potassium like bananas, carrots)
Define half-life
The half-life of a radioactive nuclide is the time taken for half the remaining unstable nuclei in a radioactive sample to decay.
Define nuclear fission
Nuclear fission is a process in which the nucleus of an atom splits and releases a huge amount of energy
What occurs during nuclear fission in terms of energy transfer and atoms
- During nuclear fission, the original atom (parent nucleus) becomes atoms of 2 different elements (daughter nuclei)
- Energy is transferred from nuclear store of unstable nucleus to
- the kinetic, internal and nuclear stores of the daughter nuclei and neutrons
- the internal store of the surroundings (to heat water into steam, which will turn turbine to generate electricity)
Define nuclear fusion
Nuclear fusion is a process in which 2 light atomic nuclei combine to form one heavier atomic nucleus and releases a huge amount of energy.
State the uses of nuclear fusion in nuclear power plants
- In nuclear power plant, nuclear fuel (eg: uranium and plutonium) undergo nuclear fission to release energy, in a self-sustaining chain reaction that is controlled.
- Nuclear fusion is not used in nuclear power plants as it requires very high temperatures and pressures.
State the uses of radioactivity related to cell damage
- Medical: γ-rays for detection of tumours and destroying brain tumours; β-particles for treatment of thyroid disorder
- Safety: γ-rays for killing microbes, sterilising medical equipment,
State the uses of radioactivity related to radioactive decay and half-life
- Geology: α-particles to determine how old an object is
State the uses of radioactivity related to penetrating abilities and ionising effects:
- Safety: α-particles in smoke detector
- Industrial: γ-rays or β-particles to measure thickness of materials
What are hazards of radioactivity?
Hazards of radioactivity can kills cells, cause cells mutation and cancer, and stunt children’s growth in human; plants and animals can suffer from mutations, stunted growth and reproduction defects.
