What Is Gallium?
Gallium is a chemical element with the symbol Ga and atomic number 31, categorized as a post-transition metal.
A soft, silvery metal that melts in your hand (mp 29.76°C).
As a post-transition metal in Period 4 and Group 13 (Boron Group), gallium's placement on the table reflects its electron configuration of [Ar] 3d¹⁰ 4s² 4p¹, which governs its bonding behavior and the type of compounds it typically forms.
Position on the Periodic Table
Gallium is located in Period 4, the first row to include the transition metals.
Within that row, gallium 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
Gallium has an atomic mass of 69.723 u and a density of 5.91 g/cm³. Its melting point is 29.76°C and its boiling point is 2204°C.
Gallium is generally softer and lower-melting than the transition metals positioned to its left on the periodic table.
Electron Configuration Explained
Gallium's electron configuration is [Ar] 3d¹⁰ 4s² 4p¹, 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 gallium's chemical reactivity and the type of bonds it forms with other elements.
History & Discovery
Gallium was formally discovered in 1875, P. de Boisbaudran, 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 Gallium Used For?
Gallium's specific properties make it useful in several applications, including:
- LED lights
- Solar cells
- Semiconductors
- Cancer treatment
- Thermometers
These uses reflect gallium's underlying classification as a post-transition metal, since the same properties that define its category in chemistry also determine where it becomes practically useful.
Fun Facts About Gallium
- Gallium melts in the palm of your hand — its melting point is just 29.76°C.
- Gallium is element number 31 on the periodic table, in Period 4 and Group 13.
- Its standard atomic mass is 69.723 u, calculated from the natural abundance of its isotopes.
Frequently Asked Questions
What is Gallium's atomic number?
Gallium has atomic number 31.
What is Gallium's chemical symbol?
Gallium's symbol is Ga.
What group and period is Gallium in?
Gallium is in Period 4, Group 13 (Boron Group).
What is Gallium's atomic mass?
Gallium's standard atomic mass is 69.723 u.