Element Facts Boron

Alison Bowler's image for:
"Element Facts Boron"
Image by: 

The semi-metal element Boron, with atomic number 5, occurs in group 13 and period 2 of the periodic table. It is solid at room temperature and melts at 2348 K (2075 C, 3767 F) then boils at 4273 K (4000 C, 7232 F). This brownish/black colored element has a density of 2.37 grams per cubic centimeter at 237 K and an atomic weight of 10.811. It has an ionization energy of 8.298 eV and an oxidation state of +3.

While compounds containing the element were known in antiquity, the pure element does not exist in nature. Scientists first isolated the pure element in 1808. In that year, the French scientists Joseph-Louis Gay-Lussac and Louis-Jaques Thenard and the British scientist Sir Humphry Davy produced a pure sample of the element in independent studies. Both the British and the French scientists produced Boron by reacting boric acid with the highly reactive alkali-metal potassium.

Today two forms of the element are available commercially. The most expensive is a pure crystalline form produced by the vapor phase reduction of either boron trichloride or tribromide with hydrogen on electrically heated filaments. Heating the boron trioxide with magnesium powder produces the cheaper, impure amorphous form of boron. An alternative production method of amorphous boron involves heating borax with carbon.

Boron occurs in some waters derived from volcanic settings as orthoboric acid. Other sources of the element include as borates in the minerals borax and colemanite. One mineral containing boron, ulexite, acts as a natural fiber optic.

There are two stable isotopes of boron. The most common of these, boron-10, which makes up 19.8% of the total, is of value in the nuclear power industry. Within that industry, boron-10 forms shields forms for nuclear radiation, control rods for nuclear reactors as well as components in the manufacture of instruments for detecting neutrons. The other naturally occurring isotope, making up 80.2% of the total, is boron-11.

Other uses of pure boron include in pyrotechnics where amorphous boron imparts a green color to fireworks and signal flares. The aerospace industry uses boron filaments, as they are both strong and light weight,

At room temperature, boron is a very poor conductor of electricity. However, when heated the element is a good electrical conductor. Optically it transmits in art of the infrared portion of the spectrum.

One of boron's compounds, boron nitride, forms a material as hard as diamond. This compound is a thermal conductor similar to metals but it is an electrical insulator.

The most commercially valuable of boron's compounds is sodium borate pentahydrate. Both the manufacturing of fiberglass and perborate bleaches uses this compound. The next most useful compound boric acid finds uses as a flame retardant an in the manufacture of textile fiberglass

Reference sources:

Los Alamos National Laboratory Chemistry Division

Web Elements

Jefferson Laboratories Science Education website

More about this author: Alison Bowler

From Around the Web

  • InfoBoxCallToAction ActionArrow
  • InfoBoxCallToAction ActionArrow
  • InfoBoxCallToAction ActionArrow