- Nucleus
- The small, dense, positively charged centre of an atom, made up of protons and neutrons.
- Isotope
- Atoms of the same element that have the same number of protons but different numbers of neutrons.
- Radioactivity
- The spontaneous emission of radiation (alpha, beta or gamma) from the unstable nuclei of certain atoms.
- Alpha particle
- A particle made of two protons and two neutrons (a helium nucleus) emitted by some radioactive nuclei; it has a positive charge and low penetrating power.
- Beta particle
- A high-speed electron emitted from the nucleus when a neutron changes into a proton; it has a negative charge and moderate penetrating power.
- Gamma ray
- A high-frequency electromagnetic wave emitted by an unstable nucleus; it has no charge and very high penetrating power.
- Radioactive decay
- The random process by which an unstable nucleus loses energy by emitting radiation and changes into a more stable nucleus.
- Half-life
- The time taken for half the radioactive nuclei in a sample to decay.
- Nuclear fission
- The splitting of a heavy nucleus into two lighter nuclei, releasing a large amount of energy.
- Nuclear fusion
- The joining of two light nuclei to form a heavier nucleus, releasing a large amount of energy, as happens in the Sun.
- Nuclear energy
- The energy released from changes in the nucleus of an atom, such as fission or fusion, described by E = mc².
- Mass defect
- The difference between the total mass of the separate nucleons and the mass of the nucleus they form, which is released as energy.
What "Nuclear Physics" terms cover
This group collects the 12 SPM Physics terms in Nuclear Physics. Getting these definitions exactly right is some of the cheapest marks in Paper 2, a "define" or "state" question wants one precise sentence with the correct unit.
The key terms to get right
- Nucleus, The small, dense, positively charged centre of an atom, made up of protons and neutrons.
- Isotope, Atoms of the same element that have the same number of protons but different numbers of neutrons.
- Radioactivity, The spontaneous emission of radiation (alpha, beta or gamma) from the unstable nuclei of certain atoms.
- Alpha particle, A particle made of two protons and two neutrons (a helium nucleus) emitted by some radioactive nuclei; it has a positive charge and low penetrating power.
- Beta particle, A high-speed electron emitted from the nucleus when a neutron changes into a proton; it has a negative charge and moderate penetrating power.
- Gamma ray, A high-frequency electromagnetic wave emitted by an unstable nucleus; it has no charge and very high penetrating power.
- Radioactive decay, The random process by which an unstable nucleus loses energy by emitting radiation and changes into a more stable nucleus.
- Half-life, The time taken for half the radioactive nuclei in a sample to decay.
- Nuclear fission, The splitting of a heavy nucleus into two lighter nuclei, releasing a large amount of energy.
- Nuclear fusion, The joining of two light nuclei to form a heavier nucleus, releasing a large amount of energy, as happens in the Sun.
- Nuclear energy, The energy released from changes in the nucleus of an atom, such as fission or fusion, described by E = mc².
- Mass defect, The difference between the total mass of the separate nucleons and the mass of the nucleus they form, which is released as energy.
How this vocabulary is examined
These terms appear as define/state items in Paper 1 and Paper 2, and inside explain and calculate questions where using the wrong word costs marks. Learn each term with its unit and one example of correct use.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)