Atomic Number – No. of Protons in Nucleus of Atom
Mass Number – Total No. of Protons and Neutrons in the Nucleus
Isotopes – Atoms have the same No. of Protons but different No. of Neutrons * Same Chemical Properties * Different Physical properties
Radio Isotopes – Unstable atoms that are radio active * An individual radioactive isotope is known as a Radioisotope
Artificial Transmutation – Creates artificial radioisotopes * Uses the process of neutron absorption
Geiger Counter is used to measure and detect radiation
Alpha Particles – (2p & 2n) Heavy and slow moving * Double positive charge * Emitted from the nucleus at less than 10% of the speed of light * Poor Penetrating ability * Travels only a few cm before losing energy
Beta Particles – Fast moving electrons * Leaves the nucleus at speeds up to 90% of the speed of light * Higher penetrating ability than alpha * Moves few metres in the air
Gamma Rays – No Mass * Travels at the speed of light * No electric charge * High penetrating ability * High frequency of Electromagnetic radiation * Can travel unlimited distance
ElectronVolt = Small distance
1eV = 1.6x10^-19 Joules Property | α Particle | β Particle | ɣ Particle | Mass | Heavy | Light | None | Charge | +2 | -1 | None | Typical Energy | -5 MeV | -1 MeV | -0.1 MeV | Range in Air | A few cm | 1or2 Metres | Many Metres | Penetration | Medium | Low | High | Ionising Ability | High | Medium | Low |
Half-Life – The time that it takes for half of the nuclei of the sample of the radioisotope to decay spontaneously. * The decay rate of an isotope is measured in terms of its Half-Life
Activity – Measured in Becquerel’s, Bq. * 1Bq = 1 disintegration per second * High activity samples are extremely dangerous
The Electro Magnetic Spectrum consists of: * Radio Waves * Micro Waves * Infrared Radiation * Visible Light * Ultraviolet Radiation * X-Rays * Gamma Rays
Ionising Radiation (High Energy) – α Particles, β Particles, Gamma Rays, X-Rays, UV-B and UV-C radiation
Non-Ionising Radiation (Low Energy) – Radio waves, Microwaves, Infrared, Visible Light, UV-A radiation
Absorbed Dose = Energy absorbed by tissue Mass of Tissue
Measure in (J/kg) or (Gy)
1Gy = 1 J/kg
Dose Equivalent = Absorbed dose x Quality Factor
Measured in Sieverts (Sv)
Effective Dose = Dose Equivalent x Weighting Factor
Measured in Sieverts (Sv)
Somatic Effects – Arise when ordinary body cells are damaged, and depend on the size of the dose. Very high doses lead to almost immediate symptoms, lower doses could lead to symptoms developing in later years. * Short Term and develops when body cells are damaged
Genetic Effects – When cells in the reproductive organs (ovaries or testes) are damaged, the body suffers genetic effects. Cells in the reproductive organs develop into ova and sperm, so if the DNA in the chromosomes of these cells is damaged, this genetic change could be passed on to developing embryo. * Long Term and occurs when cells in the reproductive organs are damaged Electricity
Charge cannot be created or destroyed, only transferred from one object to another; this is the idea of the conservation of charge.
An excess of electrons causes an object to be negatively charged, and a deficit in electrons will mean the object is positively charged.
Like charges repel and unlike charges attract. The closer the charges are to each other, the strong the force.
The Van de Graaff generator is often used as a source of electrostatic charge in the laboratory.
The Elementary Charge is the magnitude of the charge on a proton or electron. It’s the smallest charge found in nature. e = 1.602 x 10^-19 C
Electron = -e
Proton = +e