When the repulsive forces of the protons exceeds the ability of the strong nuclear force to hold them together, they are unstable. In addition, sometimes nuclei are too heavy and have too many neutrons to remain together

Alpha Particles- 2 protons and 2 neutrons Beta Particles- electron Gamma Rays- Tiny electromagnetic waves Positron Emission –positive charged electron Electeon Capture – electron combined with a proton to make a nucleus

Alpha Particles * Represented by α (alpha) * They are equivalent to the nuclei of a He atom * (+2) Charge, heavy and slow moving *Limited penetrating power, stopped by sheet of paper

Alpha Particles * Represented by α (alpha) * They are equivalent to the nuclei of a He atom * (+2) Charge, heavy and slow moving *Limited penetrating power, stopped by sheet of paper Equation Example:

Conversion From One Element to Another Through Alpha Decay

Dangers of Radon Gas

 The Radium Girls painted radium on watches. Many of them died from years of exposure to the substance. They were told it was harmless  Radium is very similar chemically to calcium and thus it entered their bones and they died of bone cancer.

Radioactive Decay Series

Beta Particles Represented by β (beta) (-) Charge, little mass, 100x faster than alpha Basically high-speed electrons Stopped by Aluminum Sheet. Changes a Neutron into a Proton

Beta Particles Equation Example:

Beta Decay Series

While it may seem it is cycling around, the difference is it keeps losing mass, thus it turns from Ra-228 to Ra-224

Gamma Particles Represented by ɣ (gamma) Electromagnetic wave, no charge (neutral) or mass Great speed, high-energy, very dangerous High penetrating power Only lead can stop them

Positron (β + ) Equivalent to a positively charged electron leaving nucleus Converts a proton into a neutron. Changes element back one But, doesn’t change overall mass. Medium penetration (can penetrate skin)

 An electron is captured by a proton in the nucleus to form a neutron.  It makes the atom go back one.  Very rare form…

Radioactivity Alpha, Beta and Gamma Particles

Half-life is a measure of the rate of decay of a radioactive element. It is the time it takes for half of the atoms to decay. Number of Half Lives Amount Remaining Time 01 1½5,730 years 2¼11,460 years 31/817,190 years 41/1622,920 years 51/3228,650 years Carbon-14 has a half life of 5730 years

Number of Half Lives Amount Remaining Time 01 1½5,730 years 2¼11,460 years

Half Lives Vary Dramatically with Isotopes Radioisotope Half-Life Polonium seconds Bismuth seconds Sodium-2415 hours Radon days Iodine days Cobalt years Radium-2261,600 years Uranium billion years