(Not in the 'N' Level Sc(Phy) syllabus)

1. Energy can occur in many forms: They are heat, light, sound, magnetism, electricity, [?] and [?] energy. There is also nuclear energy.

2. N[?] energy is the light, sound and mechanical energy caused by the changes in atoms.

There are two types of nuclear energy:
(a) Fusion is the process when two light atoms f[?] to form a third atom, and a lot of energy is given off.
(b) Fission is the process when a heavy atom is made to s[?] up into two or more lighter atoms, with a lot of energy being released.

3. Energy [?] change from one form into another. Energy changes are taking place all the time around us.

4. Fission and fusion are both used to generate electricity. This is a good use. Both can also be used in making nuclear [?]s.

5. The following can be used to detect radioactivity:
- diffusion cloud chamber
- Geiger-Muller tube ([?] tube) with ratemeter or scalar or counter

6. Radioactive decay occurs r[?]ly over space and time.

7. Alpha () radiation is a stream of h[?] nuclei (positive charge).

8. Beta () radiation is a stream of high-energy e[?]s (negative charge).

9. Gamma () radiation is high frequency electromagnetic radiation (short wavelength) with [?] charge.

10. - particles produce a [?] amount of ionisation. - particles produce [?] amount of ionisation. - rays produce hardly any ionisation.

11. - particles have the least penetrating power. A sheet of [?] can stop these particles.

12. - particles are stopped by a 5-mm thick [?] sheet.

13. - rays have the most penetrating power. They are absorbed by a 2-cm thick [?] shield.

14. The half-life of a sample of radioactive substance is defined as the time taken for [?] of the unstable nuclei to decay.

15. Some hazards of radiation:
- radiation burns
- birth defects

16. The atom is largely an empty s[?]. It has a very small nucleus compared to the entire atom.

17. The nucleus consists of [?] which are positively charged and [?] which has no charge.

18. Any atom of an element X can be represented by the nuclide notation: .

A is the [?] number (mass number). It is the total number of protons and neutrons in the nucleus.
Z is the [?] number (atomic number). It is the number of protons in the nucleus.

19. Isotopes of an element contain atoms which have the [?] proton number but [?] nucleon numbers.