About

Boron is a metalloid with several forms, the most common being amorphous boron, a dark powder, and crystalline boron, which is extremely hard. It's known for its exceptional hardness, second only to diamond, and is used to create durable fiberglass, heat-resistant borosilicate glass, and super-hard materials like boron carbide. It also serves as a crucial dopant in the semiconductor industry.

Atomic Properties

Atomic Number5

Atomic Weight10.81 u

Neutrons (common)6

Electron Configuration[He] 2s² 2p¹

Full Configuration1s² 2s² 2p¹

Electrons per Shell2, 3

Electronegativity2.04

Electron Affinity26.7 kJ/mol

Oxidation States+3

Covalent Radius88 pm

Van der Waals Radius192 pm

Ionic Radius27 pm

Periodic Table Position

Group13

Period2

BlockP

Chemical SeriesMetalloids

Physical Properties

State at STPsolid

AppearanceBlack-brown, hard, brittle metalloid.

Crystal Structurerhombohedral

Magnetic Orderingdiamagnetic

Speed of Sound16,200 m/s

Poisson Ratio0.21

Thermal Properties

Melting Point2,349 K

Boiling Point4,200 K

Thermal Expansion0 1/K

Thermal Conductivity27.4 W/(m·K)

Specific Heat1.026 J/(g·K)

Molar Heat11.087 J/(mol·K)

Heat of Fusion50.2 kJ/mol

Heat of Vaporization508 kJ/mol

Abundance

In Earth's Crust10 ppm

In Ocean4.44 ppm

In Solar System0.007 ppm

In Human Body0.26 ppm

In Universe0.001 ppm

Discovery

Discovered byJoseph Louis Gay-Lussac & Humphry Davy

Discovery Year1,808

Occurrenceprimordial

CAS Number7440-42-8

Electron Configuration

Energy

↿⇂

↿

Isotopes of Boron

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
¹⁰B	10.012937	19.9%	Stable	Stable
¹¹B	11.009305	80.1%	Stable	Stable

Interactive Visualization

Explore the 3D Bohr model of Boron in our interactive viewer.

View 3D Model of Boron