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 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
| Physical Properties | |
|---|---|
| Atomic Radius | 85 pm
|
| Molar Volume | 4.6 cm³/mol
|
| 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
|
| 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 |
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 | |
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
|
| 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 | |
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 Structure | Simple Trigonal (TET) |
| Lattice Constant | 8.73 Å
|
| Lattice Angles | 1.01334, 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. | |
| Category | Metalloids, Metalloids |
| CAS Group | IIIB |
| IUPAC Group | IIIA |
| Glawe Number | 86 |
| Mendeleev Number | 81 |
| Pettifor Number | 86 |
| Geochemical Class | |
| Goldschmidt Class | litophile |
| 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 | |
| C6 Dispersion Coefficient | 99.5 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 |
