what is radioactivity?

Answer 1

Radioactivity is the behavior of elements that undergo nuclear fission and break down into smaller elements. The masses of the 'daughter' products do not add up to the same as the mass of the 'parent'; some of the mass is converted to energy.

The energy is emitted (radiated) in one of four forms (depending on the particular element): alpha particles, which are helium nuclei (two protons and two neutrons), beta particles which are high-speed electrons, gamma rays which are very short wavelength photons or high speed neutrons.

The alpha and beta particles are not very dangerous to human beings, as they cannot penetrate our skin, so they are not dangerous unless we ingest or inhale them.

But the gamma rays and neutrons can be extremely dangerous. They can penetrate into our bodies without us feeling anything, without our being aware of it happening. They are ionizing radiation, which can cause damage to cells and to DNA. If cells are damaged, they may die; if DNA is damaged, it may lead to cancer.

There is another natural radioactive process, fusion, which gives off gamma rays and neutrons, but fusion only takes place in stars. Fusion does not take place on Earth. The only radiations we must beware of on Earth are those caused by fission reactions, whether from natural or man made sources.

Radioactivity was discovered in 1896 by Henri Bequerel of France.

Answer 2

Radioactivity was first discovered in 1896 by the French scientist Henri Becquerel while working on phosphorescent materials. These materials glow in the dark after exposure to light, and he thought that the glow produced in cathode ray tubes by X-rays might somehow be connected with phosphorescence. So he tried wrapping a photographic plate in black paper and placing various phosphorescent minerals on it. All results were negative until he tried using uranium salts. The result with these compounds was a deep blackening of the plate.

However, it soon became clear that the blackening of the plate had nothing to do with phosphorescence because the plate blackened when the mineral was kept in the dark. Also non-phosphorescent salts of uranium and even metallic uranium blackened the plate. Clearly there was some new form of radiation that could pass through paper that was causing the plate to blacken.


Alpha particles are completely stopped by a sheet of paper, beta particles by an aluminum plate. Gamma rays however, can only be reduced by much more substantial obstacles, such as a very thick piece of lead.At first it seemed that the new radiation was similar to the then recently discovered X-rays. However further research by Becquerel, Marie Curie, Pierre Curie, Ernest Rutherford and others discovered that radioactivity was significantly more complicated. Different types of decay can occur, but Rutherford was the first to realize that they all occur with the same mathematical approximately exponential formula

Answer 3

Radioactivity is the spontaneous emmision of radiation from decaying unstable material. The radiation emitted includes alpha particles, nucleons, electrons, and gamma rays.

http://en.wikipedia.org/wiki/Radioactive

Answer 4

Radioactivity is when two or more listen to one radio and can't decide between Classic fm and radio 2. It happens a lot in our household. Steve Wright generally wins.

Answer 5

radioactivity is the spontaneous disintegration of atomic nuclei with the emission of alpha, beta and gamma rays, discovered by Becquerel (accidental discovery).