can you explain 'radioactivity?

Answer 1

There are four sources of radioactivity. There is a certain number of protons and neutrons in a nucleus that make a stable nucleus. If they vary from that ratio, then the nucleus can be unstable relative to radioactive decay. Also, beyond bismuth, At. No. 83, there are no elements with stable isotopes. This seems to be because the nuclei are too big to hang together.

1. Too many neutrons: Nuclei like carbon-14 decay by emitting an electron (beta minus particle). In the nucleus, a neutron changes into a proton and emits the electron. The product is nitrogen-14. By contrast, carbon-12 and -13 are stable

2. Too few neutrons: Carbon-11 decays by positron (beta plus) emission. In tghe nucleus, a proton divides into a positron and a neutron and emits the positron. The product is boron-11.

3. Too heavy: Uranium-238 decays by alpha emission (a helium nucleus, consisting of two neutrons and two protons) to thorium-234. The loss of two protons leads to an element two atomic numbers lower. The loss of two protonsand two neutrons leads toa nucleus 4 mass units lighter.

4. Thy're just radioactive: There are two elements in the periodic table, technetium, No. 43, and promethium, At. No. 63. Apparently, it is not possible to have stable shells ofneutrons and protons, so they're not stable at all.

Answer 2

Atoms which have very high or very low neutron to proton ratios tend to decompose. When I say decompose, I mean that the nucleus is unstable and changes to pursue a more stable nuclei. When it does this, it may release a particle or just energy in the form of electromagnetic energy (light). The particle could be an alpha particle (2 Helium nuclei...He2^+2), a beta particle (high speed electron), a neutron, positron or neutrino. The new nucleus is itself radioactive in many cases. The speed of the decay is typically recorded as the half-life and these vary from seconds to hundreds of years. The half-life is the amount of time it takes for 1/2 of the nuclei to decay.

I hope that helps.

Answer 3

Maybe, but I'm sure your textbook does a much more thorough job and it will correlate more with what you will need to know about it for the test rather than my random facts about it.
Here are some sites that will help:

http://search.yahoo.com/search?p=radioactivity&fr=ush-ans