Physics · Paper 1

Atomic structure

The structure of an atom, isotopes, how the model of the atom developed, radioactive decay and nuclear radiation, nuclear equations, half-lives, contamination and irradiation, background radiation, uses and hazards of radiation, and nuclear fission and fusion.

  • 9 lessons
  • All boards

Lessons

Ticks are remembered on this device only.

Downloads

Free, no account needed.

Key terms in this chapter

All 54, gathered from every lesson.

Atom
The smallest part of an element that can exist.
Nucleus
The positively charged centre of an atom containing protons and neutrons.
Proton
A positive particle in the nucleus.
Neutron
A neutral particle in the nucleus.
Electron
A negative particle that orbits the nucleus.
Energy level
A distance from the nucleus at which an electron can be.
Atomic number
The number of protons in an atom.
Mass number
The total number of protons and neutrons.
Isotopes
Atoms of the same element with different numbers of neutrons.
Ion
An atom that has lost or gained electrons.
Element
A substance made of atoms with the same number of protons.
Nuclide
A particular type of nucleus, such as carbon-14.
Radioactive decay
The random process in which an unstable nucleus emits radiation.
Activity
The rate at which a source decays, in becquerel.
Count rate
Number of decays detected each second.
Ionising
Able to knock electrons off atoms.
Alpha particle
Two protons and two neutrons.
Gamma ray
Electromagnetic radiation from the nucleus.
Nuclear equation
An equation showing what happens to a nucleus in radioactive decay.
Balanced
The same mass number total and atomic number total on both sides.
Daughter nucleus
The nucleus formed after decay.
Alpha decay
Emission of a helium nucleus.
Beta decay
A neutron changes to a proton and an electron is emitted.
Gamma emission
Release of energy from the nucleus as electromagnetic radiation.
Half-life
The time for the number of nuclei (or the activity) to halve.
Random
Cannot be predicted for a single nucleus.
Count rate
The number of decays detected each second.
Activity
The rate of decay of a source, in becquerel.
Decay curve
A graph showing how activity falls with time.
Background
The radiation that is always around us.
Contamination
The unwanted presence of radioactive atoms on or in other materials.
Irradiation
Exposure to nuclear radiation without radioactive atoms being transferred.
Shielding
Material used to absorb radiation.
Peer review
Checking of scientific work by other scientists.
Hazard
Something that could cause harm.
Precaution
An action to reduce a risk.
Background radiation
Radiation that is around us all the time.
Cosmic rays
High-energy particles from space.
Radon
A radioactive gas from rocks.
Radiation dose
A measure of the risk of harm from radiation, in sieverts.
Millisievert
One thousandth of a sievert.
Man-made
Produced by human activity.
Tracer
A radioactive substance used to follow a process in the body.
Radiotherapy
Treating cancer using nuclear radiation.
Half-life
The time for the activity to halve.
Gamma camera
A device that detects gamma rays from a tracer.
Unwanted tissue
Tissue such as a tumour.
Risk
The chance of harm.
Nuclear fission
The splitting of a large, unstable nucleus.
Nuclear fusion
The joining of two light nuclei to form a heavier nucleus.
Chain reaction
A reaction in which the products cause more of the same reaction.
Control rods
Rods that absorb neutrons to control a reactor.
Fission products
The smaller nuclei produced by fission.
Nuclear reactor
A device in which fission is controlled.