Nuclear Chemistry

Radioactivity The result of an unstable nucleus Three main types –Alpha –Beta –Gamma

Alpha A helium atom Can result when the nucleus of a large atom breaks apart U  Th He Note that all mass is conserved. 238 =

Beta A high speed electron A neutron breaks into a proton, changing the number of protons in the nucleus and resulting in a atom of a different element, and an electron that is expelled from the nucleus Po  At e Mass of atom stays the same.

Gamma Radiation Gamma ray – photon of light Emitted when an atom that has released a beta particle “settles” down.

Table of types of Radiation

Half Life Radioactive decay occurs one atom at a time Half life is the time requires for half of the atoms that were in the starting sample to decay. Half life is a constant rate 14 C – half life around 5700 yrs

Example Start: 100 g 14 C After 5730 yrs, have 100g/2 = 50g 14 C After another 5730 yrs, have 50g/2 = 25g 14 C After the next 5730 yrs, have 25g/2 = 12.5g 14 C 14C

Nuclear Fission Fission – the breaking apart of an atom into smaller parts Method – neutron “hits” a nucleus of an atom. Energy of collision is transferred to the nucleus. If sufficient, the nucleus breaks into smaller pieces creating two new atoms of other elements. Mass is conserved.

Example

Manhattan Project New Mexico - Los Alamos, White Sands First nuclear bombs Little Boy – used “critical” mass Fat Man – conventional explosives compress atoms which then “explode”

Fusion The Power of the Stars Small nuclei are fused together to form larger nuclei.

Uses Nuclear energy -Fission produces MORE radioactive material than is consumed -Fusion produces massive amounts of energy and smaller amounts of radioactivity. Not yet available to use on Earth. -Medicine -Dating/determining ages of things