What Is Boron?
Boron, atomic number 5 and symbol B, is one of the periodic table's metalloids — elements that straddle the line between metal and nonmetal.
A metalloid used in glass, ceramics and as a neutron absorber in nuclear reactors.
As a metalloid in Period 2 and Group 13 (Boron Group), boron's placement on the table reflects its electron configuration of [He] 2s² 2p¹, which governs its bonding behavior and the type of compounds it typically forms.
Position on the Periodic Table
Boron is located in Period 2, where elements fill their second electron shell.
Within that row, boron sits in Group 13 (Boron Group), alongside elements that share a similar number of valence electrons and, by extension, similar chemical behavior.
This position is not arbitrary — the periodic table was deliberately organized so that an element's row and column reveal its expected reactivity, bonding pattern, and physical state at a glance.
Physical & Chemical Properties
Boron has an atomic mass of 10.811 u and a density of 2.37 g/cm³. Its melting point is 2076°C and its boiling point is 3927°C.
As a metalloid, boron conducts electricity better than a typical nonmetal but worse than a true metal, a property known as semiconductivity.
Electron Configuration Explained
Boron's electron configuration is [He] 2s² 2p¹, describing how its electrons are distributed across shells and subshells around the nucleus.
Reading the configuration in order shows electrons filling shells of increasing energy, following the standard Aufbau principle that explains how atomic structure builds up across the periodic table.
The outermost (valence) electrons shown in this configuration are what ultimately determine boron's chemical reactivity and the type of bonds it forms with other elements.
History & Discovery
Boron was formally discovered in 1808, Gay-Lussac, identified through the careful isolation and analytical techniques typical of that era's chemical research.
Many elements from this period were anticipated by Dmitri Mendeleev's periodic table, which successfully predicted gaps corresponding to undiscovered elements well before laboratory instruments existed to confirm them directly.
What Is Boron Used For?
Boron's specific properties make it useful in several applications, including:
- Borosilicate glass
- Fertilizers
- Nuclear control rods
- Antiseptics
- Semiconductors
These uses reflect boron's underlying classification as a metalloid, since the same properties that define its category in chemistry also determine where it becomes practically useful.
Fun Facts About Boron
- Borax (a boron compound) has been used as a cleaning agent for over 4,000 years.
- Boron is element number 5 on the periodic table, in Period 2 and Group 13.
- Its standard atomic mass is 10.811 u, calculated from the natural abundance of its isotopes.
Frequently Asked Questions
What is Boron's atomic number?
Boron has atomic number 5.
What is Boron's chemical symbol?
Boron's symbol is B.
What group and period is Boron in?
Boron is in Period 2, Group 13 (Boron Group).
What is Boron's atomic mass?
Boron's standard atomic mass is 10.811 u.