Boron - B

Atomic number

5

Atomic mass

10.81 g.mol ^-1

Electronegativity according to Pauling

2.0

Density

2.3 g.cm^-3 at 20°C

Melting point

2076 °C

Boiling point

3927 °C

Vanderwaals radius

0.098 nm

Ionic radius

0.027 nm

Isotopes

2

Electronic shell

[ He ] 2s²2p¹

Energy of first ionisation

800.5 kJ.mol ^-1

Energy of second ionisation

2426.5 kJ.mol ^-1

Energy of third ionisation

3658.7 kJ.mol ^-1

Discovered by

Sir Humphry Davy and J.L Gay-Lussac in 1808

Humans can be exposed to boron through fruit and vegetables, water, air and consumer products. we have a regular daily intake of about 2 mg and about 18 mg in out body in total.

When humans consume large amounts of boron-containing food, the boron concentrations in their bodies may rise to levels that can cause health problems. Boron can infect the stomach, liver, kidneys and brains and can eventually lead to death. When exposure to small amounts of boron takes place irritation of the nose, throat or eyes may occur. It takes 5 g of borc acid to make a person ill and 20 grams or more to put its life in danger.

Eating fish or meat will not increase the boron concentrations in our bodies, as boron does not accumulate within the tissues of animals.

Boron is an element that occurs in the environment mainly through natural processes.

Boron occurs naturally in the environment due to the release into air, soil and water through weathering. It may also occur in groundwater in very small amounts. Humans add boron by manufacturing glass, combusting coal, melting copper and through the addition of agricultural fertilizers. The concentrations of boron that are added by humans are smaller that the naturally added concentrations through natural weathering.

Boron exposure through air and drinking water is not very likely to occur, but the risk of exposure to borate dust in the workplace does exist. Boron exposure may also occur from consumer products such as cosmetics and laundry products.

Plants absorb boron from the ground and through plant-consuming animals it can end up in food chains. Boron has been found in animal tissue, but it is not likely to accumulate.

When animals absorb large amounts of boron over a relatively long period of time through food or drinking water the male reproductive organs will be affected. When animals are exposed to boron during pregnancy their offspring may suffer from birth defects or delayed development. Furthermore, animals are likely to suffer from nose irritation when they breathe in boron.