You need to know about the basic structure of atoms:
a) The basic structure of an atom is a small central nucleus composed of protons and neutrons surrounded by electrons.
b) The relative masses and relative electric charges of protons, neutrons and electrons.
c) In an atom the number of electrons is equal to the number of protons in the nucleus. The atom has no overall electrical charge.
d) Atoms may lose or gain electrons to form charged particles called ions.
e) The atoms of an element always have the same number of protons, but have a different number of neutrons for each isotope. The total number of protons in an atom is called its atomic number. The total number of protons and neutrons in an atom is called its mass number.
You also need to know about nuclear radiation:
a) Some substances give out radiation from the nuclei of their atoms all the time, whatever happens to them. These substances are said to be radioactive. Candidates should appreciate the relative size of the nucleus compared to the size of the atom. Candidates should be aware of the random nature of radioactive decay.
b) The origins of background radiation. Knowledge and understanding should include both natural sources, such as rocks and cosmic rays from
c) Identification of an alpha particle as two neutrons and two protons, the same as a helium nucleus, a beta particle as an electron from the nucleus and gamma radiation as electromagnetic radiation.
d) Nuclear equations to show single alpha and beta decay.
e) Properties of the alpha, beta and gamma radiations limited to their relative ionising power, their penetration through materials and their range in air.
f) Alpha and beta radiations are deflected by both electric and magnetic fields but gamma radiation is not.
g) The uses of and the dangers associated with each type of nuclear radiation.
h) The half-life of a radioactive isotope is the average time it takes for the number of nuclei of the isotope in a sample to halve, or the time it takes for the count rate from a sample containing the isotope to fall to half its initial level.
You also need to know about fission:
a) There are two fissionable substances in common use in nuclear reactors: uranium-235 and plutonium-239.
b) Nuclear fission is the splitting of an atomic nucleus.
c) For fission to occur, the uranium-235 or plutonium-239 nucleus must first absorb a neutron.
d) The nucleus undergoing fission splits into two smaller nuclei and two or three neutrons and energy is released.
e) The neutrons may go on to start a chain reaction.
You also need to know about fusion:
a) Nuclear fusion is the joining of two atomic nuclei to form a larger one.
b) Nuclear fusion is the process by which energy is released in stars.
c) Stars form when enough dust and gas from space is pulled together by gravitational attraction. Smaller masses may also form and be attracted by a larger mass to become planets.
d) During the ‘main sequence’ period of its life cycle a star is stable because the forces within it are balanced.
e) A star goes through a life cycle. This life cycle is determined by the size of the star.