Atomic number: 5

Average atomic mass: 10.811


The element is not found free in nature. It exists naturally as 19.78% 10B isotope and 80.22% 11B isotope. Boron has 14 total isotopes (2 stable and 12 radioactive). Boron is a non-metal. Several allotropes of boron exist; amorphous boron is a brown powder, though crystalline boron is black, hard (9.3 on Mohs' scale), and a weak conductor at room temperature. Optical characteristics of crystalline/elemental boron include the transmittance of infrared light. At standard temperatures, elemental boron is a poor electrical conductor, but is a good electrical conductor at high temperatures.


Amorphous boron is used in pyrotechnic flares to provide a distinctive green color, and in rockets as an igniter. Elemental boron is used as a dopant in the semiconductor industry, while boron compounds play important roles as light structural materials, nontoxic insecticides and preservatives, and reagents for chemical synthesis. Boron is an essential plant nutrient. Boron is also used for heat resistent alloys.


Boron has been known for thousands of years. In early Egypt, mummification depended upon an ore known as natron, which contained borates as well as some other common salts. Borax glazes were used in China from 300 AD, and boron compounds were used in glassmaking in ancient Rome.
It was isolated in 1808 by Sir Humphry Davy and Gay-Lussac and Thenard. It was found in certian volcanic spring waters in the Mojave Desert.
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