boron

• Description
• General information
• Physical data
• Radii
• Electronegativities
• Solid state structure
• Temperatures
• Enthalpies
• Ionization Enthalpies
• Isotopes
• Further information

Description

Boron is a Group 13 element. Boron has properties which are borderline between metals and non-metals. It is a semiconductor rather than a metallic conductor. Chemically it is more related to silicon than to aluminium, gallium, indium, and thallium.

Crystalline boron is inert chemically and is resistant to attack by boiling HF or HCl. When finely divided it is attacked slowly by hot concentrated nitric acid.

General information

Discoveror: Sir Humphrey Davy, Joseph-Louis Gay-Lussac, Louis-Jaques Thénard
Date discovered: 1808
Discovered at: England, France
Meaning of name: From the Arabic word "buraq" and the Persian word "burah"

Physical data

Standard state: solid at 298 K
Colour: black
Density of solid at ambient temperature/kg m^-3: 2460
Molar volume/cm³: 4.39

Radii /pm

Atomic: 87
Covalent (single bond):
Pauling radius for the ion [B]^-: no data

Valence shell orbital radius maxima (R_max)

orbital	s	p	d	f
radius	80.7	83.9	no data	no data

Electronegativities

Both values are quoted on the Pauling scale.

Pauling: 2.04
Allred Rochow: 2.01

Crystal Structure

structure: rhombohedral

The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.

Temperatures (/K)

melting point: 2349
boiling point: 4200

Enthalpies /kJ mol^-1

fusion: 50.2
vaporization: 507

single bond enthalpies:

B-F	B-Cl	B-Br	B-I	B-B
613	456	377	no data	297

Ionization enthalpies /kJ mol^-1

Number	Enthalpy
1st	800.6
2nd	2427
3rd	3659.8
4th	25026
5th	32827

Isotopes

This section gives some data for naturally occurring isotopes.

Nominal mass	Accurate mass	% natural abundance
10B	10.0129369 (3)	19.9 (2)
11B	11.0093054 (4)	80.1 (2)

Further Information

• Additional information about WebElements 1.2.2
• This is a licensed copy (here is the full list) of WebElements 1.2.2 and contains a subset of the material contained within the main version of WebElements (version 2)
• For further information please try WebElements version 2
• Sheffield Chemdex: perhaps the largest internet chemistry directory
• Sheffield Chemputer: interactive chemistry calculators on the WWW