The Periodic Table of Scarcity and Abundance
Menu

Boron

Element 5 · Metalloid

Specimen

Atomic number
5
Atomic mass
10.81
State at room temperature
Solid
Melting point
2,075 °C
Boiling point
4,000 °C
Density
2.37 g/cm³
Discovered
1808

Physical data from PubChem.1

Can I eat it?

In food and water
Allowed in food. The EU allows boric acid (E 284) and borax (E 285) as food additives, but only in caviar. Since 2009, the EU also lets food makers add boron to foods. 23

See every element.

The atom

B
ShellElectrons
1 (K) 2
2 (L) outermost 3
Total5

Configuration [He] 2s² 2p¹

2s ↑ ↓
2p ↑
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 5 protons. The outermost shell is shown in red. Electrons do not travel on rings: they fill orbitals, regions where an electron is likely to be found. The boxes are those orbitals for the electrons outside the He core, with one arrow per electron.

Related elements

Group 13
Al Aluminium Ga Gallium In Indium Tl Thallium Nh Nihonium

New elements by e-mail

Sources

  1. 1

    National Center for Biotechnology Information (PubChem), 2026. Periodic Table of Elements .

    Atomic mass, electron configuration, melting and boiling points, density and discovery year for all 118 elements.

  2. 2

    European Commission, 2011. Commission Regulation (EU) No 1129/2011 establishing a Union list of food additives , Annex, Parts B and E.

    The text as adopted by the EU in 2011, from legislation.gov.uk. Later EU amendments are not in it.

    • E 284 Boric acid 4 000 (54) only Sturgeons’ eggs (Caviar)
  3. 3

    European Commission, 2009. Commission Regulation (EC) No 1170/2009 amending Directive 2002/46/EC and Regulation (EC) No 1925/2006 , Article 2.

    The text as adopted by the EU, from legislation.gov.uk. EUR-Lex served the quote checker an empty page.

    • In Annex I, the word ‘Boron’ is added in the list in point 2.