Radiation

Radiation

1. The Nuclear Model

2. Nuclear Model

3. Nuclear Model

   • Atoms contain three sub-atomic particles called protons, neutrons and electrons. The protons and neutrons are found in the nucleus at the centre of the atom. The electrons are arranged in energy levels, or shells, around the nucleus.
   • Proton - mass of 1, charge of +1 Neutron - mass of 1, charge of 0 Electron - mass of almost zero, charge of -1
   • If an atom loses one or more electrons, it becomes a positively charged ion. If an atom gains one or more electrons, it becomes a negatively charged ion,
   • The number of electrons in an atom is always the same as the number of protons, so atoms are electrically neutral overall.

4. Isotopes

   • The number of protons in the nucleus of an atom is called its atomic number: - the atoms of a particular element have the same amount of protons - the atoms of different elemnts have different numbers of protons
   • The total number of protons and neutrons in an atom is called its mass number.
   • Isotopes are the atoms of an element with different numbers of neutrons. They have the same proton number, but different mass numbers

5. Radioactive Decay

   • The nuclei of some isotopes are unstable. They can split up or 'decay' and release radiation. Such isotopes are called radioactive isotopes or radioisotopes. When a radioactive isotope decays, it forms a different atom with a different number of protons
   • When an atom emits alpha or beta radiation, its nucleus changes. It becomes the nucleus of a different element.
   • An alpha particle is identical to a helium nucleus - the mass number goes down by 4, and the atomic number goes down by 2

6. Types of radiation

   • Alpha radiation - is the weakest, and a helium nuclei
   • Beta radiation - is stronger than alpha, consists of an electron
   • Gamma radiation - is the strongest, and consists of radiomagnetic waves

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