Boron (B)

An element of group 13 of the periodic table. There are two allotropes, amorphous boron is a brown power, but metallic boron is black. The metallic form is hard (9.3 on Mohs' scale) and a bad conductor in room temperatures. It is never found free in nature. Boron-10 is used in nuclear reactor control rods and shields. It was discovered in 1808 by Sir Humphry Davy and by J.L. Gay-Lussac and L.J. Thenard.

Atomic Number	5
Atomic Weight	10.81
Mass Number	11

Group	13
Period	2
Block	p

Protons	5 p⁺
Neutrons	6 n⁰
Electrons	5 e^-

Properties

Energy
Atomic Radius	85 pm 205 pm
Molar Volume	4.6 cm³/mol
Covalent Radius	85 pm 78 pm 73 pm 84 pm
Metallic Radius	80 pm 98 pm
Ionic Radius	1 pm 11 pm 27 pm
Crystal Radius	15 pm 25 pm 41 pm
Van der Waals Radius	180 pm 402 pm 192 pm 215 pm 192 pm 408.3 pm
Density	2.34 g/cm³ 2,080 kg/m³
Proton Affinity
Electron Affinity	0.279723 eV/particle
Ionization Energy	8.298019 eV/particle 25.15483 eV/particle 37.93058 eV/particle 259.3715 eV/particle 340.226008 eV/particle
Heat of Vaporization	504.5 kJ/mol
Heat of Fusion	23.6 kJ/mol
Heat of Formation	565 kJ/mol
Electrons
Electron Shells	2, 3
Valence Electrons	3
Electron Configuration	[He] 2s² 2p¹
Oxidation States	-5, -1, 0, 1, 2, 3
Electronegativity	12.13 eV/particle 0.184886 2.04
Electrophilicity	1.1470276511768214 eV/particle
Phases
Phase	Solid
Gas Phase
Boiling Point	4,273.15 K
Melting Point	2,350.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual
Color	Black #00ff00 #ffb5b5 #ffb5b5
Appearance	black-brown
Refractive Index
Thermodynamic Properties
Thermal Conductivity	27.4 W/(m K)
Thermal Expansion	0.000006 1/K
Molar Heat Capacity	11.087 J/(mol K)
Specific Heat Capacity	1.026 J/(g⋅K)
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
Type	Insulator
Electrical Conductivity	0.0000000001 MS/m
Electrical Resistivity	10,000 m Ω
Superconducting Point
Magnetism
Type	diamagnetic
Magnetic Susceptibility (Mass)	-0.0000000087 m³/Kg
Magnetic Susceptibility (Molar)	-0.0000000000941 m³/mol
Magnetic Susceptibility (Volume)	-0.0000214
Magnetic Ordering
Curie Point
Neel Point
Structure
Crystal Structure	Simple Trigonal (TET)
Lattice Constant	8.73 Å
Lattice Angles	1.01334, 1.01334, 1.01334
Mechanical Properties
Hardness	9.3 MPa 49,000 MPa
Bulk Modulus	320 GPa
Shear Modulus
Young Modulus
Poisson Ratio
Speed of Sound	16,200 m/s
Classification
Category	Metalloids, Metalloids
CAS Group	IIIB
IUPAC Group	IIIA
Glawe Number	86
Mendeleev Number	81
Pettifor Number	86
Geochemical Class
Goldschmidt Class	litophile
Other
Gas Basicity
Dipole Polarizability	20.5 ± 0.1 a₀
C6 Dispersion Coefficient	99.5 a₀ 99.2 a₀
Allotropes	Alpha Rhombohedral Boron, Beta Rhombohedral Boron, Alpha Tetragonal Boron
Neutron Cross Section	760
Neutron Mass Absorption	2.4
Quantum Numbers	2P1/2
Space Group	166 (R_3m)

Isotopes of Boron

Stable Isotopes	2
Unstable Isotopes	14
Radioactive Isotopes	13

⁶B

Abundance	Radioactive ☢️
Relative Atomic Mass	6.0508 ± 0.00215 Da
Mass Number	6
G-Factor
Half Life
Spin	2
Quadrupole Moment
Discovery Year
Parity	-

⁶B Decay Modes

Decay Mode	Intensity
2p (2-proton emission)	%

⁷B

Abundance	Radioactive ☢️
Relative Atomic Mass	7.029712 ± 0.000027 Da
Mass Number	7
G-Factor
Half Life	570 ± 14 ys
Spin	3/2
Quadrupole Moment
Discovery Year	1967
Parity	-

⁷B Decay Modes

Decay Mode	Intensity
p (proton emission)	100%

⁸B

Abundance	Radioactive ☢️
Relative Atomic Mass	8.024607315 ± 0.000001073 Da
Mass Number	8
G-Factor	0.51775 ± 0.00015
Half Life	771.9 ± 0.9 ms
Spin	2
Quadrupole Moment	0.0643 ± 0.0014
Discovery Year	1950
Parity	+

⁸B Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺α (β⁺-delayed α emission)	100%

⁹B

Abundance	Radioactive ☢️
Relative Atomic Mass	9.013329645 ± 0.000000969 Da
Mass Number	9
G-Factor
Half Life	800 ± 300 zs
Spin	3/2
Quadrupole Moment
Discovery Year	1940
Parity	-

⁹B Decay Modes

Decay Mode	Intensity
p (proton emission)	100%

¹⁰B

Abundance	19.65 ± 0.44
Relative Atomic Mass	10.012936862 ± 0.000000016 Da
Mass Number	10
G-Factor	0.60015453333333 ± 0.00000026666666666667
Half Life
Spin	3
Quadrupole Moment	0.0846 ± 0.0002
Discovery Year	1920
Parity	+

¹¹B

Abundance	80.35 ± 0.44
Relative Atomic Mass	11.009305166 ± 0.000000013 Da
Mass Number	11
G-Factor	1.792252 ± 0.00000066666666666667
Half Life
Spin	3/2
Quadrupole Moment	0.04059 ± 0.0001
Discovery Year	1920
Parity	-

¹²B

Abundance	Radioactive ☢️
Relative Atomic Mass	12.014352638 ± 0.000001418 Da
Mass Number	12
G-Factor	1.003 ± 0.001
Half Life	20.2 ± 0.02 ms
Spin	1
Quadrupole Moment	0.0132 ± 0.0003
Discovery Year	1935
Parity	+

¹²B Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻α (β⁻-delayed α emission)	0.6%

¹³B

Abundance	Radioactive ☢️
Relative Atomic Mass	13.017779981 ± 0.000001073 Da
Mass Number	13
G-Factor	2.1185333333333 ± 0.00033333333333333
Half Life	17.16 ± 0.18 ms
Spin	3/2
Quadrupole Moment	0.0365 ± 0.0008
Discovery Year	1956
Parity	-

¹³B Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	0.266%

¹⁴B

Abundance	Radioactive ☢️
Relative Atomic Mass	14.02540401 ± 0.000022773 Da
Mass Number	14
G-Factor	0.5925 ± 0.0025
Half Life	12.36 ± 0.29 ms
Spin	2
Quadrupole Moment	0.0297 ± 0.0008
Discovery Year	1966
Parity	-

¹⁴B Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	6.04%
2n (2-neutron emission)	%

¹⁵B

Abundance	Radioactive ☢️
Relative Atomic Mass	15.031087023 ± 0.000022575 Da
Mass Number	15
G-Factor	1.7726666666667 ± 0.01
Half Life	10.18 ± 0.35 ms
Spin	3/2
Quadrupole Moment	0.0379 ± 0.0011
Discovery Year	1966
Parity	-

¹⁵B Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	98.7%
2n (2-neutron emission)	1.5%

¹⁶B

Abundance	Radioactive ☢️
Relative Atomic Mass	16.039841045 ± 0.000026373 Da
Mass Number	16
G-Factor	0
Half Life
Spin	0
Quadrupole Moment	0
Discovery Year	2000
Parity	-

¹⁶B Decay Modes

Decay Mode	Intensity
n (neutron emission)	%

¹⁷B

Abundance	Radioactive ☢️
Relative Atomic Mass	17.046931399 ± 0.000219114 Da
Mass Number	17
G-Factor	1.7 ± 0.013333333333333
Half Life	5.08 ± 0.05 ms
Spin	3/2
Quadrupole Moment	0.0385 ± 0.0015
Discovery Year	1973
Parity	-

¹⁷B Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	63%
2n (2-neutron emission)	12%
3n (3-neutron emission)	3.5%
4n	0.4%

¹⁸B

Abundance
Relative Atomic Mass	18.055601683 ± 0.00021918 Da
Mass Number	18
G-Factor
Half Life
Spin	2
Quadrupole Moment
Discovery Year	2010
Parity	-

¹⁸B Decay Modes

Decay Mode	Intensity
n (neutron emission)	100%

¹⁹B

Abundance	Radioactive ☢️
Relative Atomic Mass	19.064166 ± 0.000564 Da
Mass Number	19
G-Factor
Half Life	2.92 ± 0.13 ms
Spin	3/2
Quadrupole Moment
Discovery Year	1984
Parity	-

¹⁹B Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	71%
2n (2-neutron emission)	17%
3n (3-neutron emission)	9.1%

²⁰B

Abundance	Radioactive ☢️
Relative Atomic Mass	20.074505644 ± 0.000586538 Da
Mass Number	20
G-Factor
Half Life
Spin	1
Quadrupole Moment
Discovery Year	2018
Parity	-

²⁰B Decay Modes

Decay Mode	Intensity
n (neutron emission)	100%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

²¹B

Abundance	Radioactive ☢️
Relative Atomic Mass	21.084147485 ± 0.00059975 Da
Mass Number	21
G-Factor
Half Life
Spin	3/2
Quadrupole Moment
Discovery Year	2018
Parity	-

²¹B Decay Modes

Decay Mode	Intensity
2n (2-neutron emission)	100%

History

Boron compounds have been known for thousands of years, but the element was not discovered until 1808 by Sir Humphry Davy and by Gay-Lussac and Thenard. Boron was not recognized as an element until it was isolated in 1808 by Sir Humphry Davy and by Joseph Louis Gay-Lussac and Louis Jacques Thénard. Jöns Jakob Berzelius identified boron as an element in 1824. From the Arabic word Buraq, Persian Burah

Discoverers	Sir H. Davy, J.L. Gay-Lussac, L.J. Thénard
Discovery Location	England/France
Discovery Year	1808
Etymology (Name Origin)	From Arabic and Persian words for borax.
Pronunciation	BO-ron (English)

Elemental boron, boron oxide, boric acid, borates and many organoboron compounds are non-toxic

Boron is an essential nutrient for all green plants

Uses

Boron oxide is used in glassmaking and ceramics. Borax is used in making fiberglass, as a cleansing fluid, a water softener, insecticide, herbicide and disinfectant. Boric acid is used as a mild antiseptic and as a flame retardant. Boron shielding is used as a control for nuclear reactors. Used with titanium & tungsten to make heat resistant alloys for jets & rockets.

Sources

Obtained from kernite, a kind of borax (Na2B4O7.10H2O). High purity boron is produced by electrolysis of molten potassium fluroborate and potassium chloride (KCl).

Abundance
Abundance in Earth's crust	10 mg/kg
Abundance in Oceans	4.44 mg/L
Abundance in Human Body	0.00007 %
Abundance in Meteor	0.00016 %
Abundance in Sun	0.0000002 %
Abundance in Universe	0.0000001 %

Nuclear Screening Constants

1	s	0.3205
2	p	2.5786
2	s	2.4238

Boron on ChemicalAid

AGROVOC ID	c_1018
Art & Architecture Thesaurus ID	300264228
Australian Educational Vocabulary ID	scot/2755
BNCF Thesaurus ID	31249
Bibliothèque nationale de France ID	12140810z
Brockhaus Enzyklopädie online ID	bor-30
CAS Registry Number	7440-42-8
ChEBI ID	27560
ChemSpider ID	4575371
DSSTOX compound identifier	DTXCID503922
DSSTox substance ID	DTXSID3023922
DrugBank ID	11203
ECHA Substance Infocard ID	100.028.319
Encyclopædia Britannica Online ID	science/boron-chemical-element
Encyclopædia Universalis ID	bore
Freebase ID	/m/025svlc
French Vikidia ID	Bore
GND ID	4007709-3
Gran Enciclopèdia Catalana ID	0085405
Great Russian Encyclopedia Online ID	1878022
HSDB ID	4482
InChI	InChI=1S/B
InChIKey	ZOXJGFHDIHLPTG-UHFFFAOYSA-N
Italian Vikidia ID	Boro
KBpedia ID	Boron
KEGG ID	C06266
LNB ID	000310483
Latvian National Encyclopedia Online ID	89038
Library of Congress authority ID	sh85015871
MeSH descriptor ID	D001895
MinDat mineral ID	43412
NDF-RT ID	N0000148267
NKCR AUT ID	ph118964
Namuwiki ID	붕소
National Diet Library ID	00563492
National Library of Israel J9U ID	987007283095205171
OmegaWiki Defined Meaning	420
OpenAlex ID	C501308230
PSH ID	5791
PubChem CID	5462311
Quora topic ID	Boron
RxNorm ID	1705
Spanish Vikidia ID	Boro
Store norske leksikon ID	bor_-_grunnstoff
Treccani ID	boro
UK Parliament thesaurus ID	8744
UMLS CUI	C0006030
UNII	N9E3X5056Q
WordNet 3.1 Synset ID	14656049-n
YSO ID	7591
ZVG number	8030

Boron (B)

Properties

Isotopes of Boron

6B

6B Decay Modes

7B

7B Decay Modes

8B

8B Decay Modes

9B

9B Decay Modes

10B

11B

12B

12B Decay Modes

13B

13B Decay Modes

14B

14B Decay Modes

15B

15B Decay Modes

16B

16B Decay Modes

17B

17B Decay Modes

18B

18B Decay Modes

19B

19B Decay Modes

20B

20B Decay Modes

21B

21B Decay Modes