La Radiación (Radioactivity)

Radioactivity is the spontaneous disintegration of atomic nuclei. The nucleus emits particles, ß particles, or electromagnetic rays during this process.Alpha ( ) Decay:
Alpha decay occurs when the nucleus spontaneously ejects an particle. An particle is really 2 protons and 2 neutrons, or an He nucleus. Sowhen an atom undergoes decay, its atomic number decreases by 2 and its atomic mass decreases by 4. particles do not penetrate much material, for they can bestopped by paper. An example of decay is the following:

Gamma Radiation:
Gamma ray emission usually occurs with and ß emission. Gamma rays have nocharge or mass, so their emission doesn't change the chemical composition of the atom. Instead, it results in a loss of radiant energy. Gamma ray emission occursbecause the nucleus is often unstable after and ß decay. There are cases where pure gamma emission occurs, and this is where an isotope exists in two forms(nuclear isomers). They have the same atomic and mass numbers, but have different nuclear-energy content. So gamma emission occurs when the isomer goes from ahigher to a lower energy form. The isotope protactinium-234 exists in two different energy states, and it emits gamma rays when undergoing transition to thelower-energy state.

Half Life:
A sample of a radioactive substance will decay into various particles. The rate of decay is measured by how long it takes forhalf the sample to decay. The decay of an individual atom is totally random, but for a large sample size, we can get a good prediction of the half life.