Boron

Boron is a chemical element with the symbol B and atomic number 5. It is a metalloid, meaning it has properties of both metals and nonmetals. Boron is found in nature as the element and in various compounds, primarily in the mineral borax. It is used in the production of glass, ceramics, and semiconductors, as well as in the manufacture of insecticides, fire retardants, and other products.

Overview

English Name:

Boron

Latin Name:

Boron

Year Discovered:

1808

Discovered By:

Humphry Davy, Louis-Jacques Thénard

Group:

13

Period:

2

Electrons:

3

CAS Number:

7440-42-8

Cost Per 100 Grams:

$100

Atomic Properties

Electronic Configuration:

1s² 2s² 2p¹

Ion Charge:

+3, -3

Ionisation Energies:

800.6 kJ/mol

Atomic Radius (Empirical):

85 pm

Atomic Radius (Calculated):

192 pm

Covalent Radius:

83 pm

Van Der Waals Radius:

192 pm

Ionisation Potential of An Atom:

8.30 eV

Electrons Per Layer:

2, 3

Atomic Multiplicities Of The Gas:

2

Atomic Weight:

10.811

Oxidation States

-3
+1
+2
+3

Reactivity

Electron Affinity:

27.6 kJ/mol

Valence:

3

Electronegativity:

2.04

Thermal Properties

Melting Point:

2076°C

Boiling Point:

3927°C

Critical Point:

Pressure: 0.1 MPa

Temperature: 2076°C

Thermal Conductivity:

27 W/(m·K)

Heat Capacity:

Specific: 1.026 J/(g·K)

Molar: 11.087 J/(mol·K)

Thermal Coefficient:

0.0000055

Enthalpy:

Fusion: 50.2 kJ/mol

Vaporisation: 507.2 kJ/mol

Atomization: 565.0 kJ/mol

Curie Temperature:

N/A

Neel Temperature:

N/A

Superconductivity Point:

N/A

Physical and Chemical Properties

State of matter (25° C/ 77°F):

Solid

Density:

Solid: 2.34 g/cm³

Molar Volume (Vmol):

4.61 L/mol

Speed of Sound (Vs):

16,200 m/s

Hardness:

9.3 (Mohs)

Bulk Modulus (K):

320 GPa

Shear Modulus (G):

160 GPa

Young's Modulus (E):

450 GPa

Color:

Brown, black

Brinell Hardness (MPa):

9300 MPa

Liquid Density (Kg/m^3):

2.08 kg/m³

Hardness of Mohs:

9.3

Refractive Index:

2.04

Vickers Hardness (MPa):

9300 MPa

Crystal Structure:

Rhombohedral

Electromagnetic Properties

Electrical Type:

Semiconductor

Resistivity:

2.55 × 10^3 Ω·m

Magnetic Type:

Diamagnetic

Superconductivity:

Not applicable

Volume Magnetic Susceptibility:

-6.4 × 10^-6

Mass Magnetic Susceptibility:

-5.9 × 10^-9 m³/kg

Molar Mass Susceptibility:

-6.4 × 10^-7 m³/mol

Electrical Conductivity:

3.9 × 10^5 S/m

Mass (γmass):

1.6726 × 10-27 kg

Mass (γmol):

1.6726 × 10-24 mol

Volume (γvol):

4.61 L

Grid Parameters

Crystal Structure:

Rhombohedral

Grid Parameters:

0.25 nm

Attitude:

N/A

Debye Temperature:

1500 K

Safety and Precautions

Signal Word:

Warning

Hazard Statements:

H302, H315, H319, H335

Precautionary Statements:

P261, P264, P270

RTECS Number:

Not available

Risk:

Flammability: Non-flammable
Health Risk: Harmful if swallowed
Reactivity: Stable
Specific Risk: None

Importance

Main sources:

Minerals, industrial processes

Main Usage:

Glass, ceramics, semiconductors

Nuclear Properties

Radioactive:

No

Isotopes:

B-10, B-11

Neutron Cross Sectional:

3.8 barns

Half Life (s):

None

Lifetime:

Stable

Prevalence

Universe:

0.001%

Sun:

0.001%

Oceans:

0.0001%

Humans:

0.00001%

Earth's Crust:

0.001%

Meteorites:

0.001%