Radium - Ra

Atomic number

88

Atomic mass

226.0254 g.mol^-1

Electronegativity according to Pauling

0.9

Density

5 g.cm^-3at 20°C

Melting point

700 °C

Boiling point

1140 °C

Vanderwaals radius

0.230 nm

Ionic radius

unknown

Isotopes

6

Electronic shell

[ Rn ] 7s²

Energy of first ionisation

509.1 kJ.mol^-1

Energy of second ionisation

975 kJ.mol^-1

Radium is naturally present in the environment in very small amounts. Because of that we are always exposed to radium and to small amounts of radiation that it releases into the environment.

Radium levels in the environment have greatly increased as a result of human activity. Humans release radium into the environment by burning coal and other fuels. Radium levels indrinking watermay be high when it is extracted from deep wells that are located near radioactive waste disposal sites.

Currently there is no information available on the amounts of radium in air and soil.

There is no evidence that exposure to naturally present levels of radium has harmful effects on human health. However, exposure to higher levels of radium may result in health effects, such as teeth fracture, anaemia and cataract. When the exposure lasts for a long period of time radium may even cause cancer and the exposure can eventually lead to death. These effects may take years to develop. They are usually caused by gamma radiation of radium, which is able to travel fairly long distances through air. Therefore contact with radium is not necessary, for radium to cause health effects.

不断产生的放射性镭decay of uranium and thorium. Radium is present at very low levels in rocks and soil and strongly attaches to those materials. It is also found in air. High concentrations of radium exist in water on some locations.

Uranium mining results in higher levels of radium in water near uranium mines. Plants absorb radium from the soil. Animals that eat these plants will accumulate radium.

Finally, radium may concentrate in fish and otheraquatic organismsand bio magnify up the food chain.