Nuclear Radiation Half-Life

What is Radiation? Penetrating rays and particles emitted by a radioactive source Result of a nuclear reaction! –Involves the changing of the atoms nuclei

Radioisotopes Isotopes –Elements with the same # of protons & electrons, but a different # of neutrons! Radioisotopes –Unstable isotopes –In nuclear rxns their nuclei undergo changes to become stable

Chemical vs. Nuclear rxns Chemical Rxns Involve the transfer or sharing of e- Nuclei are unchanged Affected by ∆ in temp, pressure & catalyst Nuclear Rxns Nuclei are changed to become stable Involve large amounts of energy being emitted Not affected by anything & cannot be stopped

Nuclear Stability Depends on the ratio of neutrons to protons in the nucleus & the overall size of the nucleus Too many or too few neutrons makes the nucleus unstable Unstable nucleus releases energy by emitting radiation during radioactive decay!

Types of Radiation 3 main types: Alpha Radiation Beta Radiation Gamma Radiation

Alpha Radiation Occurs when a helium nuclei is emitted –Called “alpha” particals Product atoms atomic # is lower by 2 & its mass # is lower by 4 Are stopped by paper!

Beta Radiation e- released when a nucleus breaks apart Product atom has the same atomic mass, but the atomic # increases by 1 Less mass than an alpha particle & can penetrate paper, but are stopped by wood or aluminum foil

Gamma Radiation High energy photons –Electromagnetic radiation Have no mass or charge, so atomic # is unchanged VERY DANGEROUS! –Can penetrate even wood!

Nuclear Decay Nuclear force Attractive force between protons & neutrons that are really close together in the nucleus Stronger than the electromagnetic repulsions Keeps nucleus together!

Half-Life Time it takes for half of the nuclei to decay into its stable daughter