Boron is the chemical element with atomic number 5, symbol B
Boron is the head of group 13 of the periodic table. Along with lithium and beryllium, it is one of the few light elements that have escaped the main nucleosynthesis processes (primordial nucleosynthesis and stellar nucleosynthesis). Their (low) cosmic abundance is attributable to cosmic spallation (interstellar bombardment of heavier elements by cosmic rays). In foods, it is present as boric acid or borate.
The single boron body is a trivalent metalloid. It is rather rare in the earth’s crust and the solar system, but more abundant on the surface of the Earth, in particular in the form of borates mainly of borax9, but also of boric acid. It constitutes about 0.001% of the earth’s crust, or 10 ppm on average (in particular 5 mg / kg in basalts).
Uses of Boron
Boron is often used as a fuel for rocket ignition and as a fire generator in engineering.
In the environment, this element is found in cleaning powders and borax preservatives. Borax is widely used in the manufacture of cleaners. Borax oxide is also frequently used in borosilicate glass factories (in Pyrex). Borax oxide can make glass heat resistant and stronger. Fiberglass in textiles also uses borosilicate as a base. Boron is used in the manufacture of fireworks to give it a green color.
The boron isotope 10 can absorb neutrons very well. Because of this property, in chemistry, the boron isotope 10 is used in controlling nuclear reactors, as a shield for nuclear radiation and can also be used in instruments to detect the presence of neutrons in a sample.
Food sources of boron
The foods richest in boron are plants: fruits, vegetables (in particular mushrooms and leafy vegetables), potatoes, legumes, nuts (walnuts, hazelnuts, etc.), cocoa and cereals. Meats, fish, dairy products, are much less provided. There is also boron in drinks, water, fruit juices and alcoholic beverages (wines, ciders, beer).
This element is mainly found in vegetables and fruits, while meat products contain small amounts of this element. Here are foods rich in boron:
Vegetables such as tomatoes and long beans.
Fruits such as grapes, apples, pears, raisins and kiwi.
Nuts such as almonds and peanuts.
It is an element that occurs naturally in the environment.
Humans can be exposed to boron from fruits and vegetables, water, air, consumer products.
Eating fish or meat does not increase the boron concentration in our body, because boron does not accumulate in animal tissues.
Exposure to this element in air or water is unlikely to occur, but the risk of exposure to boron dust in the workplace exists. You can also be exposed to boron with certain consumer products such as cosmetics and laundry detergents.
When humans consume large amounts of food containing this element, the boron concentration in our body can increase to unhealthy levels. It can infect the stomach, liver, kidneys and brain and can eventually lead to death. When exposed to small amounts of Boron, it can irritate the nose, throat or eyes.
Environmental effect of boron
It is naturally present in the environment: air, water and soil. It can also be found in very small amounts in groundwater. The production of glass, the combustion of coal, the smelting of copper and the addition of agricultural fertilizer increases the presence of boron in the environment. The concentration of boron introduced into the environment as a result of human activities is lower than that of boron present naturally.
Plants take up boron from the soil and through animals feeding on plants. It can thus enter the food chain. This element has been found in animal tissue, but it usually does not accumulate.
When animals take in large amounts of chlorine (intake of water or food) over a relatively long period of time male reproductive organs can be affected. When animals are exposed to this element during pregnancy, the young can suffer from deformities or late development. In addition animals can suffer from nasal irritation when inhaling boron.
Boron compounds (Arabic بورق – buraq, Persian burah “bright”), have been known for thousands of years. In ancient Egypt, the mummification process depended on natron, a mineral containing impurities of borates as well as other more common salts. It has been known by metallurgists and ceramists since the earliest times. The Chinese have been using a high borax clay at least since – 300, and the Romans have used this element compounds for the manufacture of glass.
This element was not isolated until 1808 by Sir Humphry Davy, Gay-Lussac and Baron Louis Jacques Thénard, who obtained a purity of 50%. They did not, however, identify substance as an element; this was done by Jöns Jacob Berzélius in 1824. Henri Moissan delivered the first purified samples and the first sample of pure boron was obtained, from boron sesquioxide, by the American chemist Ezekiel Weintraub in 1909.
Boron in the periodic table
|Atomic number (Z)||5|
|Group||group 13 (boron group)|
|Electron configuration||[He] 2s2 2p1|
|Electrons per shell||2, 3|
|Phase at STP||solid|
|Melting point||2349 K (2076 °C, 3769 °F)|
|Boiling point||4200 K (3927 °C, 7101 °F)|
|Density when liquid (at m.p.)||2.08 g/cm3|
|Heat of fusion||50.2 kJ/mol|
|Heat of vaporization||508 kJ/mol|
|Molar heat capacity||11.087 J/(mol·K)|
|P (Pa)||1||10||100||1 k||10 k||100 k|
|at T (K)||2348||2562||2822||3141||3545||4072|
|Oxidation states||−5, −1, 0, +1, +2, +3 (a mildly acidic oxide)|
|Electronegativity||Pauling scale: 2.04|
|Atomic radius||empirical: 90 pm|
|Covalent radius||84±3 pm|
|Van der Waals radius||192 pm|
|Speed of sound thin rod||16,200 m/s (at 20 °C)|
|Thermal expansion||β form: 5–7 µm/(m·K) (at 25 °C)|
|Thermal conductivity||27.4 W/(m·K)|
|Electrical resistivity||~106 Ω·m (at 20 °C)|
|Magnetic susceptibility||−6.7·10−6 cm3/mol|
|Discovery||Joseph Louis Gay-Lussac and Louis Jacques Thénard (30 June 1808)|
|First isolation||Humphry Davy (9 July 1808)|
Main isotopes of boron
Boron (5B) naturally occurs as isotopes 10B and 11B, the latter of which makes up about 80% of natural boron. There are 13 radioisotopes that have been discovered, with mass numbers from 7 to 21, all with short half-lives, the longest being that of 8B, with a half-life of only 770 milliseconds (ms) and 12B with a half-life of 20.2 ms. All other isotopes have half-lives shorter than 17.35 ms. Those isotopes with mass below 10 decay into helium (via short-lived isotopes of beryllium for 7B and 9B) while those with mass above 11 mostly become carbon.
|Main isotopes of boron|
|10B content is 19.1–20.3% in natural samples, with the remainder being 11B.|
Photo source: Wikimedia Commons
Photo explanations: Crystalline boron.