Name boron
Symbol B
Atomic Weight 10.811
Atomic Number 5
CAS ID 7440-42-8
Group Number 13
Group Name (none)
Period Number 2
Origin of Name Arabic, buraq
Year Discovered 1808
Discovery Credits L. J. Lissac and L. J. Thenard in Paris, France and Sir Humphrey Davy in London, UK.
Class Semi-Metallic
Color black
Standard State Solid at 77 F & 298 K
Description Non-metal with several allotropes. Amorphous boron is a dark powder un-reactive to oxygen, water, acids, and alkalis. Forms metal borides with most metals. Used in borosilicate glass, detergents, and fire retardants. Strong neutron capture ability is put to best use as a moderator for nuclear reactions involving neutrons.

Diagnostic tests: 
Many compounds containing boron tinge the flame test an intense yellowish green. This effect is masked if the mineral contains sodium. The flame test color lasts only an instant and may be confused with the green flame color produced from barium minerals.
In a small quantity of sulfuric acid solution, add 10 drops of methyl alcohol. Stir, and set fire to the mixture. The first flash of green flame confirms the presence of boron. If the green flame color occurs after the first flash of flame, barium or copper is present.

Back to Elements Table Page