radioactive decay and nuclear radiation

• what is radioactive decay?


  the spontaneous emission of penetrating and ionising radiation from the nucleus of an atom.
• why does radioactive decay occur?


  it occurs in order to become more stable, by changing the amount of protons in the nucleus.
• what is alpha radiation?


  it consists of particles, composed of two protons and two neutrons (a helium nucleus), it has the greatest ionising power.
• what is gamma radiation?


  it consists of electromagnetic radiation from the nucleus of an atom , it is uncharged so has no mass so its emission doesn't change the amount of protons or neutrons in a nucleus. so the mass and charge of the nucleus are both unchanged.
• what is beta radiation


  it consists of fast moving electrons emitted from the nucleus, it is less ionising than alpha but more ionising than gamma. beta has too many neutrons compared to its protons. a neutron in the nucleus changes to a proton and a beta particle (an electron) which is instantly emitted to the relative mass is zero and its relative charge is -1.
• what happens when an unstable nucleus particles emits a beta particle?

  the atomic number goes up by one and its mass number is unchanged and a neutron turns to a proton.

  the charge of the nucleus is increased but the mass is unchanged

  numbers on the top = total no. of protons and neutrons after change is equal to the number before the change

  numbers on bottom = shows that the total charge is equal to the charge before the change
• what happens when an alpha particle is emitted?

  its atomic number goes down by two and its mass number goes down by four

  the mass and charge of the nucleus are both reduced

  numbers along top = total number of protons and neutrons after change

  numbers along bottom = show number of protons after change is equal to number before change
• neutron emission 


  neutrons are emitted by some radioactive substances as a result of alpha particles colliding with unstable nuclei in the substance, such collision causes these nuclei to become even more unstable and emit a neutron which can pass through substances much easier than alpha or beta as they are uncharged.