Decay

• When does radioactive decay occur?

  -It occurs in an unstable nuclei in order to become a stable nuclei
• Is it possible to predict when a nucleus will decay?

  -No its impossible to predict when a nucleus will decay
• What is the activity of a radioisotope measured by?

  -Becquerels (Bq) and 1Bq = 1 decay / count per second
• What is Alpha decay?

  -Alpha decay is radioactivity. It is when an alpha particle is emitted from a nucleus
• What is an alpha particle?

  -It is a helium nucleus and contains 2 protons and 2 neutrons
• What happens when an alpha particle is emitted from a nucleus?

  -The nucleus has 2 fewer protons therefore its atomic number (Porton number) decreases by 2

  • 2 fewer neutrons and 2 fewer protons means 4 mass is lost
  • A new element is formed
• Here is alpha decay what happens to the mass and atomic number after alpha decay?

  -Mass number decreases by 4 therefore -4

  -Atomic number decreases by 2 therefore -2

  
• What is beta decay?

  Radioactive decay process in which a beta particle (electron or positron) is emitted from the nucleus of an atom.
• What happens in beta decay?

  -One of the neutrons decays into a proton and an electron and the electron is emitted from the nucleus
• What happens when a beta particle is emitted from a nucleus?

  -The nucleus has one more proton, so the atomic number increases by 1 as only the electron is emitted

  • 1 less neutron but the mass number is unchanged
  • New element is formed
• What happens to the mass and atomic number in beta decay?

  Mass: Stays the same Atomic number: Increases by 1
• What is gamma decay?

  -In gamma decay gamma rays are emitted from a nucleus

  -They have no charge or mass therefore no changes occur in the nucleus
• What is an example of gamma decay?

  Nuclear decay. IMAGE Nothing changes

  
• What is half life?

  The time it takes for half of a radioactive substance to decay.
• This is a half life graph and it showcases the time it takes for the number of radioactive nuclei to half

  
• What are all the different sources of background Radiation?

  Cosmic rays, Nuclear accidents and testing, terrestrial sources (such as rocks), and medical , finding and treating.