Boron is a metalloid with an atomic number of 5 in the periodic table of elements. It’s found in an amount of 0.00086 percent in the Earth’s crust. Being a member of the boron family of periodic table elements, this chemical substance has three valence electrons. While boron is labeled as a non-metalic element, the other chemical elements of the boron family are classified as post-transition metals.
Chemical and Physical Properties of Boron
The symbol in the periodic table of elements: (B)
Atomic number: 5
Atomic weight (mass): 10.81 g.mol -1
Group number: 13
Color: Dark-brown to black (powder) or silvery-gray, lustrous element resembling metal
Physical state: Solid (metalloid)
Half-life: From 17.35 ms to 770 ms
Electronegativity according to Pauling:
Density: 2.3 g.cm-3 at 20°C
Melting point: 2076 °C
Boiling point: 3927 °C
Van der Waals radius: 0.098 nm
Ionic radius: 0.027 nm
Isotopes: 2 naturally occurring isotopes [11B (80.1%) and 10B (19.9%)]
Most characteristic isotope:11B
Electronic shell: [He] 2s22p1
The energy of the first ionization: 800.5 kJ.mol -1
The energy of the second ionization: 2426.5 kJ.mol -1
The energy of the third ionization: 3658.7 kJ.mol -1
Discovery date: In 1808 by Sir Humphrey Davy, Joseph Louis Gay-Lussac, and Louis-Jaques Thénard
With the periodic table symbol (B), atomic number 5, atomic mass of 10.81 g.mol -1, and electronic configuration [He] 2s22p1, boron is a substance that comes in several forms, among which the powder or the solid metal-like form are its most common occurrences. In its pure form, boron is able to transmit infrared light.
Boron is a very hard substance and has good conducting properties at high temperatures, but cannot conduct electricity at standard temperatures. It reaches its boiling point at 3927 °C, while the melting point of this chemical element is achieved at 2076 °C. This member of the boron family of elements in the periodic table has an electronegativity of X according to Pauling, whereas the atomic radius according to van der Waals is 0.098 nm.
How Was Boron Discovered?
This chemical element has been known by the Egyptians, Tibetans, Arabians, and the Chinese for thousands of years before its official modern-times discovery. The deposits of crystallized boron located at Lake Yamdrok Cho in Tibet were the main source of borax for hundreds of years before boron was isolated and recognized as a chemical element.
In this way, the ancient civilizations have been familiar with the properties and use of this chemical element long before its lab formulation performed by Joseph Louis Gay-Lussac, Louis Jacques Thénard, and Sir Humphry Davy.
In 1808, the French chemists Joseph Louis Gay-Lussac (1778 – 1850) and Louis-Jaques Thénard (1777 – 1857) and the British chemist and inventor Sir Humphrey Davy (1778 – 1829) have tried to isolate boron in their respective experiments that aimed to trigger a reaction between boric acid and sodium.
Unfortunately, their efforts resulted only in a compound with a high percentage of boron (around 70-80%). But then Louis Jacques Thénard tried to trigger a reaction between potassium and boric acid, and with this chemical experiment, he succeeded in isolating a brand new chemical element that was labeled as boracium.
In 1824, the Swedish chemist Jöns Jakob Berzelius managed to isolate boron and identify its properties as a chemical element. Half a century later, after boron was isolated from its compounds, it was produced only in an impure form.
This chemical element wasn’t under the spotlight until the 20th century, when in 1909 the American chemist Ezekiel W. Weintraub succeeded in producing boron in its pure form by triggering a reducing reaction between boron halides and hydrogen.
How Did Boron Get Its Name?
The name of this chemical element with characteristic dark-gray to black, glittery color comes from the arabic word “buraq – بورق”, used as a reference to the chemical compound borax, and the Latin word “carbo”, meaning “coal”, that refers to the physical appearance of this chemical element of the periodic table.
Where Can You Find Boron?
Traces of this element can be located in stardust and meteorites where it’s produced by the impact of cosmic rays on the cosmic materials. This process is defined as the x-process.
Volcanic springs sometimes contain traces of boric acid. Since it cannot be found in free elemental form on Earth, boron is mostly extracted from compounds, such as borax, colemanite, ulexite, or kernite. However, the use of the colemanite ore has been brought to a minimum due to the arsenic traces in it.
The largest boron deposits have been located in Turkey, which is the biggest boron producer in the world (together with the United States). The Adirondack region of northern New York State is also rich in boron-bearing minerals.
Boron in the Human Body
Together with vanadium, boron is one of the trace elements that supports our health. Together with vitamin K, boron supports bone health by preventing the loss of calcium. Between 1870 and 1920, and again during World War II, this mineral was used as a food preservative.
The Role of Boron In Human Nutrition
As a supplement, boron supports the brain function and its cognitive abilities. Furthermore, boron supplementation is used for increasing athletic performance and the building of muscle mass in male bodybuilders due to its ability to raise testosterone levels. It’s also considered that boron intake can ease the adverse effects of chemotherapy. In combination with chromium and vanadium, boron is thought to have effects on weight loss.
A clinical trial entitled as “”Effect of dietary boron on mineral, estrogen, and testosterone metabolism in postmenopausal women”. FASEB J. 1 (5): 394–7.” analyses the effects of dietary boron on mineral, estrogen, and testosterone metabolism in postmenopausal women.
The research confirmed the fact that postmenopausal women are among the ones who also benefit from an additional intake of boron since it increases the estrogen levels, thus easing the postmenopausal symptoms that typically cause dyscomfort. The credits for this trial are awarded to Nielsen FH, Hunt CD, Mullen LM, and Hunt JR.
In another study, Naghii MR, et al. (2011) prove the importance of boron as a trace mineral. This study confirms the vital role this mineral has in the evolution of life on Earth, by being an essential part of the metabolic processes in all living beings – humans, animals, and plants.
Boron supplementation can also increase the Vitamin D-3 serum levels in patients with depleted cholecalciferol. However, prior to any supplement intake, please consult a healthcare provider nearby for more detailed information on the health benefits and hazards related to the supplement.
Kashin-Beck Disease Related to Boron Deficiency
Boron deficiency, combined with germanium and molybdenum deficiency, may lead to Kashin-Beck disease. It’s a chronic and degenerative disease of the joints and bones that mostly affects the people of Tibet, China, North Korea, and Siberia. The symptoms experienced by the affected individuals include:
- Aches in the bones and joints;
- Stiff and deformed joints of hands, fingers, elbows, ankles, and knees;
- Necrosis of the cartilage of hands, fingers, elbows, ankles, and knees.
Such cases only reinforce the nutritional essentiality of boron regarding the health of bones and joints. Boron supplementation is recommended when there is a high risk factor of osteoporosis or cardiovascular diseases.
The Versatile Uses of Boron in Everyday Life
Even though boron is rarely found in its elemental form, due to the everyday use of both boron and boron compounds, they have many applications in various industries. In this regard, borax and boron oxide are two of the most commercially exploited boron compounds. This chemical element has been applied in medicine, as well as in some industrial branches.
The Use of Boron for Pyrotechnics and Sport Equipment
Pyrotechnic flares use boron as an igniter. Also, due to its high-strength properties, boron is used in the making of fishing rods and golf-clubs.
The Use of Boron in the Glass and Textile Industry
Borosilicate glass (Pyrex) is made of boric oxide which gives it heat-resistant properties and hardness. Borosilicate glass is further used for insulations, as well as for making fibreglass textiles.
The Use of Boron for Cleansing
Many abrasive detergents and cleaners contain boron as a main ingredient. In addition, boron is used in insecticides as a strong chemical agent against cockroaches, ants, and fleas.
The Use of Boron for Magnets, MRI, and Audio-Systems
The strongest type of magnet is the neodymium magnet. It’s made by melting and mixing neodymium, iron, and/or boron into an alloy. Being the strongest permanent magnet, the neodymium magnet is used in cell phones, DVD and CD players, headphones, loudspeakers, microphones, machines whose work is based on MRI (Magnetic Resonance Imaging), etc.
The Use of Boron in Nuclear Reactors
Nuclear reactors that control uranium or plutonium fission rates use special rods made of boron, indium, cadmium, or silver. The main reason for the use of the 10B isotope in nuclear reactors is its high ability to absorb neutrons.
The Use of Boron in Wood Industry
Boron is used in wood preservatives. It acts as a powerful bactericide/fungicide and also destroys the wood-eating insects. When the boron compounds come into contact with wood with a p-H value of 4 to 5, they turn into boric acid.
The Use of Boron in Medicine
The boron-10 isotope is used in the treatment of some invasive malignant tumors that are mainly located in the brain. Namely, this isotope of boron has been implemented in an experimental non-surgical treatment labeled as Boron neutron capture therapy (BNCT).
High doses of boron applied in the treatment of osteoarthritis and rheumatoid arthritis have also proven to be beneficial for the affected individuals.
Boron and the Plants
Boron is a micronutrient that is essential for the health and growth of plants. It supports many metabolic processes, including the formation of the plant’s cell wall, the stability of the cell’s membranes, and transporting nutrients to the growing parts of the plant.
How Dangerous Is Boron?
Both the elemental form of boron and its compounds are non-toxic to people and nature. However, it’s considered to have a cumulative toxic effect. This means that when the consumed or absorbed quantities of boron pass the estimated non-toxic level, this chemical element can lead to side effects including:
- Abdominal pain.
According to the World Health Organisation (WHO) and the Food and Nutrition Board of the Institute of Medicine, the boron levels in drinking water are limited to 2.4 mg of boron per liter in order to avoid the toxic health effects caused by boron accumulation in the body.
Isotopes of Boron
This chemical element has two stable isotopes: boron-10 and boron-11. The atomic weight of the other 11 isotopes of synthetically produced boron ranges from 7-17.
|Z||N||Isotopic mass (Da)
[n 2][n 3]
[n 6][n 7]
|Natural abundance (mole fraction)|
|Excitation energy||Normal proportion||Range of variation|
|7B||5||2||7.029712(27)||570(14) × 10−24 s
|8B[n 9]||5||3||8.0246073(11)||770(3) ms||β+, α||2 4
|9B||5||4||9.0133296(10)||800(300) × 10−21 s
|p, α||2 4
|12B||5||7||12.0143526(14)||20.20(2) ms||β− (98.4%)||12
|β−, α (1.6%)||8
|13B||5||8||13.0177800(11)||17.33(17) ms||β− (99.72%)||13
|β−, n (0.28%)||12
|14B||5||9||14.025404(23)||12.5(5) ms||β− (93.96%)||14
|β−, n (6.04%)||13
|15B||5||10||15.031088(23)||9.93(7) ms||β−, n (93.6%)||14
|β−, 2n (0.4%)||13
|16B||5||11||16.039842(26)||> 4.6 × 10−21 s||n||15
|17B[n 11]||5||12||17.04693(22)||5.08(5) ms||β−, n (63.0%)||16
|β−, 2n (11.0%)||15
|β−, 3n (3.5%)||14
|β−, 4n (0.4%)||13
|18B||5||13||18.05560(22)||< 26 ns||n||17
|19B[n 11]||5||14||19.06417(56)||2.92(13) ms||β−, n (71%)||18
|β−, 2n (17%)||17
|21B||5||16||21.08302(97)#||< 260 ns
Allotropes of Boron
Boron is a chemical element that can be found in several amorphous and crystalline forms.
The crystalline forms of boron can be:
- α-rhombohedral boron molecule;
- β-rhombohedral boron molecule;
- α-tetragonal boron molecule;
- Γ-orthorhombic boron molecule;
- cubic boron molecule;
- two-dimensional boron molecule (borophene);
- quasi-spherical boron molecule;
- amorphous boron molecule;
- β-tetragonal boron molecule.
The following is a tabular representation of the properties assigned to the allotropes of boron.
|Vickers hardness (GPa)||42||45||50–58|
|Bulk modulus (GPa)||224||184||227|
|Band gap (eV)||2||1.6||~2.6||2.1||0.56–0.71|
|Color||Crystals are clear red||Black and opaque, with metallic lustre||Dark to shiny silver-grey||Black/red[n 2]||Dark grey||Black to brown[n 3]||Opaque black|
|Year first reported||1958||1943/1973[n 4]||1957||1960||2009||1808||1911|
List of Boron Compounds
The chemical compounds that interact with boron are numerous. Boron can be a part of hydrides, fluorides, chlorides, bromides, iodides, oxides, sulfides, nitrides, etc. The most significant compounds of boron are borax (sodium borate decahydrate), sodium tetraborate decahydrate, sodium borate, and borium oxide.
When in the form of a powder, boron does not react with oxygen, acids, water, or alkali elements. Borides are some of the most difficult compounds to be created synthetically.
The following is a list containing some of the boron compounds:
- Boranylium ions;
- Boron arsenide;
- Boron carbide;
- Boron carbides;
- Boron monofluoride;
- Boron monofluoride monoxide;
- Boron monoxide;
- Boron nitride;
- Boron nitride aerogel;
- Boron nitride nanosheet;
- Boron nitride nanotube;
- Boron oxide;
- Boron phosphate;
- Boron phosphide;
- Boron porphyrins;
- Boron suboxide;
- Boron sulfide;
- Boron tribromide;
- Boron trichloride;
- Boron trifluoride;
- Boron trifluoride etherate;
- Boron triiodide;
- Boron trioxide;
- Borophosphosilicate glass;
- Borosilicate glass;
- Caesium dodecaborate;
- Diboron tetrachloride;
- Diboron tetrafluoride;
- Potassium trispyrazolylborate;
- Synthesis of hexagonal boron nitride;
5 Interesting Facts And Explanations
- The boron family of elements in the periodic table comprises boron, aluminium, gallium, indium, and thallium.
- There is 2×10-7% of boron in the Sun.
- The human body naturally contains 0.00007% of boron. In addition, we ingest from 2-4 mg of boron every day.
- When used as an ignitor for pyrotechnic flares, boron gives out a green light.
- Jöns Jakob Berzelius is considered to be one of the founders of modern chemistry, alongside Robert Boyle, John Dalton, and Antoine Lavoisier. Due to his great achievements in modern chemistry, the “father of Swedish chemistry” has been honored with a day dedicated to his work and life. Berzelius Day is celebrated on 20th of August.
Chemical Property and physical property of element Boron
Symbol of Boron: B
Atomic Number of Boron: 5
Group of Boron: Non-Metal
Crystal Structure of Boron: Rhombohedral
Atomic Weight of Boron: 10.811
Shells of Boron: 2,3
Orbitals of Boron: [He] 2s2 2p1
Valence of Boron: 3
Melting Point of Boron: 2450
Boiling Point of Boron: 3931.15
Electro Negativity of Boron: 2.04
Covalent Radius of Boron: 0.82 Å
Ionic Radius of Boron: .23 (+3) Å
Atomic Radius of Boron: 1.17 Å
Atomic Volume of Boron: 04.6 cm³/mol
Name Origin of Boron: From Arabic and Persian words for borax.
Discovered of Boron By: Sir H. Davy, J.L. Gay-Lussac, L.J. Thénard
Pronounced of Boron: BO-ron
Oxydation States of Boron: 3
Density of Boron: 2.34 g/cm³
Uses of Boron: Used with titanium & tungsten to make heat resistant alloys for jets & rockets.
Description of Boron: Allotropic forms include diamonds and graphite. Sixth most abundant element in the universe.