Boron facts for kids

	beryllium ← boron → carbon
Appearance
	black-brown;
General properties
Name, symbol, number	boron, B, 5
Group, period, block	13, 2, p
Standard atomic weight	{{{atomic mass}}} g/mol
Electron configuration	[He] 2s2 2p1
Electrons per shell	2, 3 (Image)
Physical properties
Phase	solid
Liquid density at m.p.	2.08 g/cm3
Melting point	2349 K, 2076 °C, 3769 °F
Boiling point	4200 K, 3927 °C, 7101 °F
Heat of fusion	50.2 kJ/mol
Heat of vaporization	508 kJ/mol
Specific heat capacity	(25 °C) 11.087 J/(mol·K)
Vapor pressure
Atomic properties
Oxidation states	3, 2, 1, −1, −5; ((a mildly acidic oxide))
Electronegativity	2.04 (Pauling scale)
Ionization energies;	1st: {{{1st ionization energy}}} kJ/mol
	2nd: {{{2nd ionization energy}}} kJ/mol
	3rd: {{{3rd ionization energy}}} kJ/mol
Atomic radius	90 pm
Covalent radius	84±3 pm
Van der Waals radius	192 pm
Miscellanea
Crystal structure	rhombohedral
Magnetic ordering	diamagnetic
Electrical resistivity	(20 °C) ~106Ω·m
Thermal conductivity	(300 K) 27.4 W/(m·K)
Thermal expansion	(25 °C) β form: 5–7 µm/(m·K)
Speed of sound (thin rod)	(20 °C) 16,200 m/s
Mohs hardness	~9.5
CAS registry number	7440-42-8
Most stable isotopes
	Main article: Isotopes of boron
	10B content may be as low as 19.1% and as high as 20.3% in natural samples. 11B is the remainder in such cases.

Boron in a tube

Boron is a chemical element. It has the chemical symbol B. It has the atomic number 5. It is a metalloid (it has properties of a metal and a non-metal). Much boron is found in chemical compounds in its ore borax. Boron is never found free in nature.

Two types of boron are found (allotropes). Amorphous boron is a brown powder and metallic (crystalline) boron is black and hard and a weak conductor at room temperature. Boron is the 5th element in the periodic table it is part of the earths surface Pure boron is used as a dopant (a substance added to semiconductors to change how it behaves with electricity) in the semiconductor industry. Chemical compounds of boron are important as to make strong materials not weigh very much, as nontoxic insecticides and preservatives, and for chemical synthesis.

Plants need boron in them to live. Very small amounts of boron are needed in animal's bodies so that they are very healthy. How it keeps animals healthy is not known in a lot of detail.

Boron was discovered by Sir Humphry Davy, an English chemist, in 1808.

Boron melts at 2075 °C (3767 °F), and boils at 4000 °C (7232 °F).

Images for kids

Sassolite
Boron chunks
Ball-and-stick model of tetraborate anion, [B4O5(OH)4]2−, as it occurs in crystalline borax, Na2[B4O5(OH)4]·8H2O. Boron atoms are pink, with bridging oxygens in red, and four hydroxyl hydrogens in white. Note two borons are trigonally bonded sp2 with no formal charge, while the other two borons are tetrahedrally bonded sp3, each carrying a formal charge of −1. The oxidation state of all borons is III. This mixture of boron coordination numbers and formal charges is characteristic of natural boron minerals.
Boron (III) trifluoride structure, showing "empty" boron p orbital in pi-type coordinate covalent bonds
Ball-and-stick model of superconductor magnesium diboride. Boron atoms lie in hexagonal aromatic graphite-like layers, with a charge of −1 on each boron atom. Magnesium(II) ions lie between layers
Neutron cross section of boron (top curve is for 10B and bottom curve for 11B)
A fragment of ulexite
Borosilicate glassware. Displayed are two beakers and a test tube.
Unit cell of B4C. The green sphere and icosahedra consist of boron atoms, and black spheres are carbon atoms.
Boron toxicity in rose leaves.