Phosphorus - P

Atomic number

15

Atomic mass

30,9738 g.mol ^-1

Electronegativity according to Pauling

2,1

Density

1,82 g/ml at 20°C

Melting point

44,2 °C

Boiling point

280 °C

Vanderwaals radius

1,04 Å

Ionic radius

0,34 Å

Atomic radius

1,28 Å

Electronic shell

[Ne]3s23p3

Energy of first ionisation

10,118 eV

Discovered by

Hennig Brandt in 1669

Phosphorus can be found in the environment most commonly as phosphates. Phosphates are important substances in the human body, because they are a part of DNA materials and they take part in energy distribution. Phosphates can also be found commonly in plants.

Phosphate is a dietary requirement, the recommended intake is 800 mg/day, a normal diet provides between 1000 and 2000 mg/day, depending on the extent to which phosphate rich foods are consumed.

Humans have changed the natural phosphate supply radically by addition of phosphate-rich manures to the soil and by the use of phosphate-containing detergents. Phosphates were also added to a number of foodstuffs, such as cheese, sausages and hams.

Too much phosphate can cause health problems, such as kidney damage and osteoporosis. Phosphate shortages can also occur. These are caused by extensive use of medicine. Too little phosphate can cause health problems.

Phosphorus in its pure form has a white colour. White phosphorus is the most dangerous form of phosphorus that is known to us. When white phosphorus occurs in nature this can be a serious danger to our health. White phosphorus is extremely poisonous and in many cases exposure to it will be fatal.

In most cases people that died of white phosphorus exposure had been accidentally swallowing rat poison. Before people die from white phosphorus exposure they often experience nausea, stomach cramps and drowsiness.

White phosphorus can cause skin burns. While burning, white phosphorus may cause damage to the liver, the heart or the kidneys.

White phosphorus

White phosphorus enters the environment when industries use it to make other chemicals and when the army uses it as ammunition. Through discharge of wastewater white phosphorus ends up in surface waters near the factories that use it.

White phosphorus is not likely to spread, because it reacts with oxygen fairly quickly. When phosphorus ends up in air through exhausts it will usually react with oxygen right away to be converted into less harmful particles. However, when phosphorus particles are in air they may have a protective coating that prevents chemical reactions.

In water, white phosphorus is not reacting with other particles that quickly and as a result it will accumulate in the bodies of aquatic organisms. In soil phosphorus will remain for several days before it is converted into less harmful substances. But in deep soils and the bottom of rivers and lakes phosphorus may remain for a thousand years or so.

Phosphates

Phosphates have many effects upon organisms. The effects are mainly consequences of emissions of large quantities of phosphate into the environment due to mining and cultivating. During water purification phosphates are often not removed properly, so that they can spread over large distances when found in surface waters.

Due to the constant addition of phosphates by humans and the exceeding of the natural concentrations, the phosphor cycle is strongly disrupted.

The increasing phosphor concentrations in surface waters raise the growth of phosphate-dependent organisms, such as algae and duckweed. These organisms use great amounts of oxygen and prevent sunlight from entering the water. This makes the water fairly unliveable for other organisms. This phenomenon is commonly known as eutrophication.