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Technical data for Boron

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Overview
NameBoron
SymbolB
Atomic Number5
Atomic Weight10.811
Density2.46 g/cm3
Melting Point2075 °C
Boiling Point4000 °C

Thermal properties
PhaseSolid
Melting Point2075 °C
Boiling Point4000 °C
Absolute Melting Point2348 K
Absolute Boiling Point4273 K
Critical PressureN/A
Critical TemperatureN/A
Heat of Fusion50 kJ/mol
Heat of Vaporization507 kJ/mol
Heat of CombustionN/A
Specific Heat1030 J/(kg K)[note]
Adiabatic IndexN/A
Neel PointN/A
Thermal Conductivity27 W/(m K)
Thermal Expansion6×10-6 K-1

Bulk physical properties
Density2.46 g/cm3
Density (Liquid)2.08 g/cm3
Molar Volume4.3947×10-6
Brinell HardnessN/A
Mohs Hardness9.3 MPa
Vickers Hardness4.9×104 MPa
Bulk Modulus320 GPa
Shear ModulusN/A
Young ModulusN/A
Poisson RatioN/A
Refractive IndexN/A
Speed of Sound1.62×104 m/s
Thermal Conductivity27 W/(m K)
Thermal Expansion6×10-6 K-1

Reactivity
Valence3
Electronegativity2.04
ElectronAffinity26.7 kJ/mol
Ionization Energies
800.6, 2427.1, 3659.7, 25025.8, 32826.7 kJ/mol

Health and Safety
Autoignition PointN/A
FlashpointN/A
Heat of CombustionN/A
DOT Hazard ClassN/A
DOT NumbersN/A
EU NumberN/A
NFPA Fire Rating3
NFPA HazardsN/A
NFPA Health Rating2
NFPA Reactivity Rating0
RTECS NumberRTECSED7350000
NFPA LabelNFPA Label

Classifications
Alternate NamesNone
Names of Allotropes
AlphaRhombohedralBoron, BetaRhombohedralBoron, AlphaTetragonalBoron
Blockp
Group13
Period2
Electron Configuration[He]2s22p1
ColorBlack
Discovery
1808 in France and United Kingdom
Gas phaseN/A
CAS NumberCAS7440-42-8
CID NumberCID5462311
Gmelin NumberN/A
NSC NumberN/A
RTECS NumberRTECSED7350000

Electrical properties
Electrical TypeInsulator
Electrical Conductivity0.0001 S/m
Resistivity10000 m Ω
Superconducting PointN/A

Magnetic properties
Magnetic TypeDiamagnetic
Curie PointN/A
Mass Magnetic Susceptibility-8.7×10-9
Molar Magnetic Susceptibility-9.41×10-11
Volume Magnetic Susceptibility-0.0000214

Abundances
% in Universe1×10-7%
% in Sun2×10-7%
% in Meteorites0.00016%
% in Earth's Crust0.00086%
% in Oceans0.00044%
% in Humans0.00007%

Atomic dimensions and structure
Atomic Radius87 pm
Covalent Radius82 pm
Van der Waals RadiusN/A
Crystal StructureSimple Trigonal
Lattice Angles
1.01334, 1.01334, 1.01334
Lattice Constants
506, 506, 506 pm
Space Group NameR_ 3m
Space Group Number166

Nuclear Properties
Half-LifeStable
LifetimeStable
Decay ModeN/A
Quantum Numbers2P1/2
Neutron Cross Section755
Neutron Mass Absorption2.4
Known Isotopes
6B, 7B, 8B, 9B, 10B, 11B, 12B, 13B, 14B, 15B, 16B, 17B, 18B, 19B
Stable Isotopes
10B, 11B
Isotopic Abundances
10B19.9%
11B80.1%


Notes on the properties of Boron:

Specific Heat: Value given for solid rhombic form.

Up to date, curated data provided by
Mathematica's ElementData function from Wolfram Research, Inc.

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