Boron

Boron (B)

Boron is the 5th element in the periodic table and has a symbol of B and atomic number of 5. It has an atomic weight of 10.810 and a mass number of 11. Boron has five protons and six neutrons in its nucleus, and five electrons in two shells. It is located in group thirteen, period two and block p of the periodic table. 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 Number5
Atomic Weight10.81
Mass Number11
Group13
Period2
Blockp
Protons5 p+
Neutrons6 n0
Electrons5 e-
Animated Bohr Model of B (Boron)

Properties

Physical Properties
Atomic Radius
85 pm
Molar Volume
Covalent Radius
85 pm
Metallic Radius
80 pm
Ionic Radius
1 pm
Crystal Radius
15 pm
Van der Waals Radius
192 pm
Density
2.34 g/cm³
Energy
Proton Affinity
Electron Affinity
0.279723 eV/particle
Ionization Energy
8.298019 eV/particle
Ionization Energies of B (Boron)
Heat of Vaporization
504.5 kJ/mol
Heat of Fusion
23.6 kJ/mol
Heat of Formation
565 kJ/mol
Electrons
Electron Shells2, 3
Bohr Model: B (Boron)
Valence Electrons3
Lewis Structure: B (Boron)
Electron Configuration[He] 2s2 2p1
Enhanced Bohr Model of B (Boron)
Orbital Diagram of B (Boron)
Oxidation States-5, -1, 0, 1, 2, 3
Electronegativity
2.04
Electrophilicity
1.1470276511768214 eV/particle
Phases
PhaseSolid
Gas Phase
Boiling Point
4,273.15 K
Melting Point
2,350.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual

Boron is a Black. B has a CPK of #00ff00, Jmol of #ffb5b5, and MOLCAS GV of #ffb5b5. The Appearance of Element 5 is black-brown.

Color
Black
Appearanceblack-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
TypeInsulator
Electrical Conductivity
0.0000000001 MS/m
Electrical Resistivity
10,000 m Ω
Superconducting Point
Magnetism
Typediamagnetic
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

The Crystal Structure of Boron is TET. The lattice constant of B is 8.73 Å. The lattice angles of Element 5 are 1.01334, 1.01334, 1.01334.

Crystal StructureSimple Trigonal (TET)
Lattice Constant
8.73 Å
Lattice Angles1.01334, 1.01334, 1.01334
Mechanical Properties

Boron has a Mohs hardness of 9.3 MPa, and Vickers of 49000 MPa. The Bulk Modulus of B is 320 GPa. The Speed of Sound of Element 5 is 16200 m/s.

Hardness
9.3 MPa
Bulk Modulus
320 GPa
Shear Modulus
Young Modulus
Poisson Ratio
Speed of Sound
16,200 m/s
Classification

The CAS Group of Boron is IIIB. The IUPAC Group of B is IIIA. The Glawe Number of Element 5 is 86. The Mendeleev Number of Boron (B) is 81. The Pettifor Number of Boron is 86. The Goldschmidt Class of B is litophile.

CategoryMetalloids, Metalloids
CAS GroupIIIB
IUPAC GroupIIIA
Glawe Number86
Mendeleev Number81
Pettifor Number86
Geochemical Class
Goldschmidt Classlitophile
Other

The Dipole Polarizability of Boron is 20.5 plus or minus 0.1 a₀. B has a C6 Dispersion Coefficient (CD) of 99.5 a₀, and C6 Dispersion Coefficient (GB) of 99.2 a₀. The Allotropes of Element 5 are Alpha Rhombohedral Boron, Beta Rhombohedral Boron, Alpha Tetragonal Boron. The Neutron Cross Section of Boron (B) is 760. The Neutron Mass Absorption of Boron is 2.4. The Quantum Numbers of B is 2P1/2. The Space Group of Element 5 is 166 (R_3m).

Gas Basicity
Dipole Polarizability
20.5 ± 0.1 a₀
C6 Dispersion Coefficient
99.5 a₀
AllotropesAlpha Rhombohedral Boron, Beta Rhombohedral Boron, Alpha Tetragonal Boron
Neutron Cross Section
760
Neutron Mass Absorption
2.4
Quantum Numbers2P1/2
Space Group166 (R_3m)

Isotopes of Boron

Stable Isotopes2
Unstable Isotopes14
Radioactive Isotopes13

6B

AbundanceRadioactive ☢️
Relative Atomic Mass
6.0508 ± 0.00215 Da
Mass Number6
G-Factor
Half Life
Spin2
Quadrupole Moment
Discovery Year
Parity-

6B Decay Modes
Decay ModeIntensity
2p (2-proton emission)%

7B

AbundanceRadioactive ☢️
Relative Atomic Mass
7.029712 ± 0.000027 Da
Mass Number7
G-Factor
Half Life
570 ± 14 ys
Spin3/2
Quadrupole Moment
Discovery Year1967
Parity-

7B Decay Modes
Decay ModeIntensity
p (proton emission)100%

8B

AbundanceRadioactive ☢️
Relative Atomic Mass
8.024607315 ± 0.000001073 Da
Mass Number8
G-Factor
0.51775 ± 0.00015
Half Life
771.9 ± 0.9 ms
Spin2
Quadrupole Moment
0.0643 ± 0.0014
Discovery Year1950
Parity+

8B Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+α (β+-delayed α emission)100%

9B

AbundanceRadioactive ☢️
Relative Atomic Mass
9.013329645 ± 0.000000969 Da
Mass Number9
G-Factor
Half Life
800 ± 300 zs
Spin3/2
Quadrupole Moment
Discovery Year1940
Parity-

9B Decay Modes
Decay ModeIntensity
p (proton emission)100%

10B

Abundance
19.65 ± 0.44
Relative Atomic Mass
10.012936862 ± 0.000000016 Da
Mass Number10
G-Factor
0.60015453333333 ± 0.00000026666666666667
Half Life
Spin3
Quadrupole Moment
0.0846 ± 0.0002
Discovery Year1920
Parity+

11B

Abundance
80.35 ± 0.44
Relative Atomic Mass
11.009305166 ± 0.000000013 Da
Mass Number11
G-Factor
1.792252 ± 0.00000066666666666667
Half Life
Spin3/2
Quadrupole Moment
0.04059 ± 0.0001
Discovery Year1920
Parity-

12B

AbundanceRadioactive ☢️
Relative Atomic Mass
12.014352638 ± 0.000001418 Da
Mass Number12
G-Factor
1.003 ± 0.001
Half Life
20.2 ± 0.02 ms
Spin1
Quadrupole Moment
0.0132 ± 0.0003
Discovery Year1935
Parity+

12B Decay Modes
Decay ModeIntensity
β (β decay)100%
βα (β-delayed α emission)0.6%

13B

AbundanceRadioactive ☢️
Relative Atomic Mass
13.017779981 ± 0.000001073 Da
Mass Number13
G-Factor
2.1185333333333 ± 0.00033333333333333
Half Life
17.16 ± 0.18 ms
Spin3/2
Quadrupole Moment
0.0365 ± 0.0008
Discovery Year1956
Parity-

13B Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)0.266%

14B

AbundanceRadioactive ☢️
Relative Atomic Mass
14.02540401 ± 0.000022773 Da
Mass Number14
G-Factor
0.5925 ± 0.0025
Half Life
12.36 ± 0.29 ms
Spin2
Quadrupole Moment
0.0297 ± 0.0008
Discovery Year1966
Parity-

14B Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)6.04%
2n (2-neutron emission)%

15B

AbundanceRadioactive ☢️
Relative Atomic Mass
15.031087023 ± 0.000022575 Da
Mass Number15
G-Factor
1.7726666666667 ± 0.01
Half Life
10.18 ± 0.35 ms
Spin3/2
Quadrupole Moment
0.0379 ± 0.0011
Discovery Year1966
Parity-

15B Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)98.7%
2n (2-neutron emission)1.5%

16B

AbundanceRadioactive ☢️
Relative Atomic Mass
16.039841045 ± 0.000026373 Da
Mass Number16
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year2000
Parity-

16B Decay Modes
Decay ModeIntensity
n (neutron emission)%

17B

AbundanceRadioactive ☢️
Relative Atomic Mass
17.046931399 ± 0.000219114 Da
Mass Number17
G-Factor
1.7 ± 0.013333333333333
Half Life
5.08 ± 0.05 ms
Spin3/2
Quadrupole Moment
0.0385 ± 0.0015
Discovery Year1973
Parity-

17B Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)63%
2n (2-neutron emission)12%
3n (3-neutron emission)3.5%
4n0.4%

18B

Abundance
Relative Atomic Mass
18.055601683 ± 0.00021918 Da
Mass Number18
G-Factor
Half Life
Spin2
Quadrupole Moment
Discovery Year2010
Parity-

18B Decay Modes
Decay ModeIntensity
n (neutron emission)100%

19B

AbundanceRadioactive ☢️
Relative Atomic Mass
19.064166 ± 0.000564 Da
Mass Number19
G-Factor
Half Life
2.92 ± 0.13 ms
Spin3/2
Quadrupole Moment
Discovery Year1984
Parity-

19B Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)71%
2n (2-neutron emission)17%
3n (3-neutron emission)9.1%

20B

AbundanceRadioactive ☢️
Relative Atomic Mass
20.074505644 ± 0.000586538 Da
Mass Number20
G-Factor
Half Life
Spin1
Quadrupole Moment
Discovery Year2018
Parity-

20B Decay Modes
Decay ModeIntensity
n (neutron emission)100%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

21B

AbundanceRadioactive ☢️
Relative Atomic Mass
21.084147485 ± 0.00059975 Da
Mass Number21
G-Factor
Half Life
Spin3/2
Quadrupole Moment
Discovery Year2018
Parity-

21B Decay Modes
Decay ModeIntensity
2n (2-neutron emission)100%
Boron
Electron shell 005 Boron

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

DiscoverersSir H. Davy, J.L. Gay-Lussac, L.J. Thénard
Discovery LocationEngland/France
Discovery Year1808
Etymology (Name Origin)From Arabic and Persian words for borax.
PronunciationBO-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
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

1s0.3205
2p2.5786
2s2.4238