7.15 describe the results of Geiger and Marsden’s experiments with gold foil and alpha particles Geiger and Marsden made an experiment with alpha particle. They shoot alpha radiation to a thin gold foil. The gold foil was surround by zinc sulphide screen which...
7.16 describe Rutherford’s nuclear model of the atom and how it accounts for the results of Geiger and Marsden’s experiment and understand the factors (charge and speed) which affect the deflection of alpha particles by a nucleus After the experiment of Geiger and...
7.13 describe the uses of radioactivity in medical and non-medical tracers, in radiotherapy, and in the radioactive dating of archaeological specimens and rocks Radioactive isotopes are used as tracers to help doctors indentify diseased organs. The tracer is swallowed...
7.17 understand that a nucleus of U-235 can be split (the process of fission) by collision with a neutron, and that this process releases energy in the form of kinetic energy of the fission products Fission: If unstable nuclei split up to form stable nuclei, the...
7.18 understand that the fission of U-235 produces two daughter nuclei and a small number of neutrons When a radioactive isotope splits it forms a stable nuclei which is called daughter nuclei. Uranium-235 produce two daughter nuclei of barium-144 and krypton-89 and...
7.19 understand that a chain reaction can be set up if the neutrons produced by one fission strike other U-235 nuclei When a U-325 splits, it gives out three neutrons. This three neutrons again hit other uranium nucleus and gives out nine neutrons. These nine neutrons...
7.20 understand the role played by the control rods and moderator when the fission process is used as an energy source to generate electricity. In a chain reaction, huge amount of energy are produced which is used to generate electricity. In the chain reaction if the...
7.12 use the concept of half-life to carry out simple calculations on activity Plot the activity of the graph against time. Point out the half of the activity and draw line to match the time as done in the figure. The time is your half-life.
7.14 describe the dangers of ionising radiations, including Radiation can cause mutations in living organisms Radiation can damage cells and tissue The problems arising in the disposal of radioactive waste and describe how the associated risks can be reduced. Ionising...
7.7 understand how to complete balanced nuclear equations In a nuclear equation, in the left hand side the total mass number should be equal to the mass number in the right hand side. And the atomic number should be equal in both sides. Here, Uranium experienced an...
7.8 understand that ionising radiations can be detected using a photographic film or a Geiger-Muller detector Photographic film is a traditional way to detect ionising radiation. Ionising radiations imprints photographic plates. Geiger Muller tube is used to measure...
7.9 explain the sources of background radiation Background radiation have many sources. Billions of years ago, when the earth formed, it contained many radioactive isotopes. Some of them are still decaying in the Earth’s crust. Violent nuclear reaction in stars are...
7.10 understand that the activity of a radioactive source decreases over a period of time and is measured in Becquerels Radioactive substance keeps decaying in a random process. As it decays, its activity is reduced over a period of time. The unit of Radioactivity is...
7.11 understand the term ‘half-life’ and understand that it is different for different radioactive isotopes “Half-Life” is the amount of time taken for the activity of any radioactive substance to reduce to half. Each radioactive isotope decays in different speeds. So...
7.6 describe the effects on the atomic and mass numbers of a nucleus of the emission of each of the three main types of radiation Alpha decay: In alpha decay, alpha particles takes away 4 nucleons with itself which reduce the mass number of the element by 4. Alpha...
7.5 describe the nature of alpha and beta particles and gamma rays and recall that they may be distinguished in terms of penetrating power Radiation Ionising power Penetrating range in air Example of range in air Radiation stopped by Alpha,α strong weak 5-8cm paper...
7.1 use the following units: Becquerel (Bq), centimetre (cm), hour (h), minute (min), second (s) Unit of radioactivity: Becquerel (Bq) Unit of length: centimetre (cm) Unit of time: hour (h) Unit of time: minute (min) Unit of time: second (s)
7.2 describe the structure of an atom in terms of protons, neutrons and electrons and use symbols such as (14/6)C to describe particular nuclei An atom is a tiny particle with nucleus in the centre and electrons orbiting it. A nucleus is made up of proton and neutron....
7.3 understand the terms atomic (proton) number, mass (nucleon) number and isotope Atomic Number: Atomic number is the number of protons in an atom Mass number: Mass number is the addition number of protons and neutrons Isotope: Isotope is an element which have the...
7.4 understand that alpha and beta particles and gamma rays are ionising radiations emitted from unstable nuclei in a random process When a unstable nuclei decay they give out ionising radiation. Ionising radiation causes atom to gain or lose electrons to form ions....