Boron | Properties, Uses, & Facts (2024)

chemical element


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Also known as: B

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Key People:
Joseph-Louis Gay-Lussac
Sir Humphry Davy
William Nunn Lipscomb, Jr.
Suzuki Akira
Related Topics:
chemical element
boron group element

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boron (B), chemical element, semimetal of main Group 13 (IIIa, or boron group) of the periodic table, essential to plant growth and of wide industrial application.

Element Properties
atomic number5
atomic weight[10.806, 10.821]
melting point2,200 °C (4,000 °F)
boiling point2,550 °C (4,620 °F)
specific gravity2.34 (at 20 °C [68 °F])
oxidation state+3
electron configuration1s22s22p1

Properties, occurrence, and uses

Pure crystalline boron is a black, lustrous semiconductor; i.e., it conducts electricity like a metal at high temperatures and is almost an insulator at low temperatures. It is hard enough (9.3 on Mohs scale) to scratch some abrasives, such as carborundum, but too brittle for use in tools. It constitutes about 0.001 percent by weight of Earth’s crust. Boron occurs combined as borax, kernite, and tincalconite (hydrated sodium borates), the major commercial boron minerals, especially concentrated in the arid regions of California, and as widely dispersed minerals such as colemanite, ulexite, and tourmaline. Sassolite—natural boric acid—occurs especially in Italy.

Boron was first isolated (1808) by French chemists Joseph-Louis Gay-Lussac and Louis-Jacques Thenard and independently by British chemist Sir Humphry Davy by heating boron oxide (B2O3) with potassium metal. The impure amorphous product, a brownish black powder, was the only form of boron known for more than a century. Pure crystalline boron may be prepared with difficulty by reduction of its bromide or chloride (BBr3, BCl3) with hydrogen on an electrically heated tantalum filament.

Limited quantities of elemental boron are widely used to increase hardness in steel. Added as the iron alloy ferroboron, it is present in many steels, usually in the range 0.001 to 0.005 percent. Boron is also used in the nonferrous-metals industry, generally as a deoxidizer, in copper-base alloys and high-conductance copper as a degasifier, and in aluminum castings to refine the grain. In the semiconductor industry, small, carefully controlled amounts of boron are added as a doping agent to silicon and germanium to modify electrical conductivity.

Britannica Quiz118 Names and Symbols of the Periodic Table Quiz

In the form of boric acid or borates, traces of boron are necessary for growth of many land plants and thus are indirectly essential for animal life. Typical effects of long-term boron deficiency are stunted, misshapen growth; vegetable “brown heart” and sugar beet “dry rot” are among the disorders due to boron deficiency. Boron deficiency can be alleviated by the application of soluble borates to the soil. In excess quantities, however, borates act as unselective herbicides. Gigantism of several species of plants growing in soil naturally abundant in boron has been reported. It is not yet clear what the precise role of boron in plant life is, but most researchers agree that the element is in some way essential for the normal growth and functioning of apical meristems, the growing tips of plant shoots.

Pure boron exists in at least four crystalline modifications or allotropes. Closed cages containing 12 boron atoms arranged in the form of an icosahedron occur in the various crystalline forms of elemental boron.

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Crystalline boron is almost inert chemically at ordinary temperatures. Boiling hydrochloric acid does not affect it, and hot concentrated nitric acid only slowly converts finely powdered boron to boric acid (H3BO3). Boron in its chemical behaviour is nonmetallic.

In nature, boron consists of a mixture of two stable isotopesboron-10 (19.9 percent) and boron-11 (80.1 percent); slight variations in this proportion produce a range of ±0.003 in the atomic weight. Both nuclei possess nuclear spin (rotation of the atomic nuclei); that of boron-10 has a value of 3 and that of boron-11, 3/2, the values being dictated by quantum factors. These isotopes are therefore of use in nuclear magnetic resonance spectroscopy, and spectrometers specially adapted to detecting the boron-11 nucleus are available commercially. The boron-10 and boron-11 nuclei also cause splitting in the resonances (that is, the appearance of new bands in the resonance spectra) of other nuclei (e.g., those of hydrogen atoms bonded to boron).

The boron-10 isotope is unique in that it possesses an extremely large capture cross section (3,836 barns) for thermal neutrons (i.e., it readily absorbs neutrons of low energy). The capture of a neutron by a nucleus of this isotope results in the expulsion of an alpha particle (nucleus of a helium atom, symbolized α):

Boron | Properties, Uses, & Facts (4)

Since the high-energy alpha particle does not travel far in normal matter, boron and some of its compounds have been used in the fabrication of neutron shields (materials not penetrable by neutrons). In the Geiger counter, alpha particles trigger a response, whereas neutrons do not; hence, if the gas chamber of a Geiger counter is filled with a gaseous boron derivative (e.g., boron trifluoride), the counter will record each alpha particle produced when a neutron that passes into the chamber is captured by a boron-10 nucleus. In this way, the Geiger counter is converted into a device for detecting neutrons, which normally do not affect it.

The affinity of boron-10 for neutrons also forms the basis of a technique known as boron neutron capture therapy (BNCT) for treating patients suffering from brain tumours. For a short time after certain boron compounds are injected into a patient with a brain tumour, the compounds collect preferentially in the tumour; irradiation of the tumour area with thermal neutrons, which cause relatively little general injury to tissue, results in the release of a tissue-damaging alpha particle in the tumour each time a boron-10 nucleus captures a neutron. In this way destruction can be limited preferentially to the tumour, leaving the normal brain tissue less affected. BNCT has also been studied as a treatment for tumours of the head and neck, the liver, the prostate, the bladder, and the breast.

Boron | Properties, Uses, & Facts (2024)


What are 5 facts about boron? ›

Interesting Facts about Boron
  • Boron is a tough element – very hard, and very resistant to heat. ...
  • Boron is an essential nutrient for all green plants.
  • Boron in its crystalline form is very unreactive. ...
  • Unusually, the universe's atoms of boron were not made by nuclear fusion within stars and were not made in the big bang.

What are the uses of boron? ›

Amorphous boron is used as a rocket fuel igniter and in pyrotechnic flares. It gives the flares a distinctive green colour. The most important compounds of boron are boric (or boracic) acid, borax (sodium borate) and boric oxide. These can be found in eye drops, mild antiseptics, washing powders and tile glazes.

What are three ways boron is useful? ›

Modern uses of borate-mineral concentrates, borax, boric acid, and other refined products include glass, fiberglass, washing products, alloys and metals, fertilizers, wood treatments, insecticides, and microbiocides. The chemistry of boron is reviewed from the point of view of its possible health effects.

What is boron daily life? ›

Borates are everywhere—from smartphone touchscreens to automotive fluids to the insulation that keeps your home's temperature comfortable. It strengthens glass and protects wood for years. Boron is even an essential micronutrient for growing crops.

Why is boron so rare? ›

Specifically, the rare and fragile light nuclei, lithium, beryllium and boron (LiBeB) are not generated in the normal course of stellar nucleosynthesis (except 7Li, in the galactic disk) and are, in fact, destroyed in stellar interiors.

What makes boron special? ›

Boron is a multipurpose element. It's a crucial nutrient for plants, an important component in the nuclear industry and the main ingredient of a bizarre fluid called oobleck. Perched next to carbon on the Periodic Table of Elements, boron is a metalloid, a substance with both metallic and nonmetallic properties.

What does boron do for the female body? ›

Boron may have antioxidant effects. People commonly use boron for boron deficiency and vagin*l yeast infections. It is also used for athletic performance, menstrual cramps, osteoarthritis, osteoporosis, and many other conditions, but there is no good scientific evidence to support many of these uses.

Can you take boron every day? ›

The World Health Organization estimates that an acceptable safe range of boron intakes for adults is 1–13 mg/day [8].

What food has the most boron? ›

What foods provide boron?
  • Fruits and fruit juices, such as raisins, peaches, and prune and grape juices.
  • Avocados and potatoes.
  • Legumes, such as peanuts, beans, and green peas.
  • Coffee, milk, cider, wine, and beer.
Jan 15, 2021

Who should not take boron? ›

Suggested Dose: No recommended dose has been established. Safety Considerations: Avoid taking boron supplements if you have kidney disease or problems with kidney function.

Does boron help you sleep? ›

Boron may help those with chronic fatigue by improving sleep.

What does boron do for the brain? ›

Assessments of cognitive and psychom*otor function in humans found that boron deprivation results in poorer performance on tasks of motor speed and dexterity, attention and short-term memory.

What are the 5 elements of boron? ›

boron group element, any of the six chemical elements constituting Group 13 (IIIa) of the periodic table. The elements are boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), and nihonium (Nh).

What is a fun fact about the boron group? ›

Boron produces a green flame. Boron is beneficial for the treatment of arthritis. Ununtrium-is a man-made, radioactive element. Boron is used in making light composite materials for aircraft.

Does boron have 5 or 6 electrons? ›

Atomic Mass10.811 atomic mass units
Number of Protons5
Number of Neutrons6
Number of Electrons5
9 more rows

Why does boron only need 6? ›

Boron wants 6 electrons. This is because boron tends to share electrons rather than give or take. An atom can only share as many electrons as it has in its valence shell. So, boron can only share three electrons.

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