Gallium (Ga)
“The metal that melts in a warm fist at 29.8 °C — and that lights up phone screens as brilliant GaN LEDs.”
How its electrons are arranged
Computed from the aufbau principle, with known real-world exceptions applied automatically.
The notes
Characteristics
- Melts at 29.8 °C — lower than a hot Dhaka afternoon — yet boils only near 2400 °C, one of the widest liquid ranges of any element.
- Electron configuration [Ar] 3d¹⁰ 4s² 4p¹ — three valence electrons, so it shares Group 13 with boron and aluminium and usually forms Ga³⁺ compounds.
- Combines with arsenic and nitrogen into GaAs and GaN — semiconductors that convert electricity straight into LED and laser light.
- Like water, it expands slightly on freezing; liquid gallium also wets glass and leaves mirror-bright streaks wherever it flows.
- A key ingredient of Galinstan (gallium-indium-tin alloy), the non-toxic liquid metal that replaces mercury in modern thermometers.
A soft, silvery-blue metal that looks like a calm cousin of mercury yet is safe to touch. It melts at just 29.8 °C — the grip of a hand or a cup of hot tea will turn a spoon-shaped solid piece into a shining puddle.
Where you meet it
✦ Uses
- Gallium nitride (GaN) blue and white LEDs — the invention behind the 2014 chemistry Nobel that lights phone screens, bulbs and billboards.
- Gallium arsenide (GaAs) chips in smartphones and satellites — faster than silicon and doubling as the laser diodes that carry internet traffic through optical fibre.
- Galinstan medical thermometers — mercury-free and safe, now standard in hospitals as mercury instruments are phased out.
- Gallium-arsenide solar panels on satellites and space probes, which keep making power where ordinary silicon panels would fade.
◍ Everyday examples
- The smartphone in your pocket hides a sprinkling of gallium in its screen’s LED backlight and its high-frequency signal chips.
- On a 35 °C summer day in Bangladesh, a gallium spoon left outdoors would quietly melt into a shiny puddle.
- Gallium never occurs free in nature — it hides in traces inside bauxite and zinc ores, so refineries rescue it as a by-product.
History & name
In 1871 Mendeleev left a blank in his new periodic table for an undiscovered element he called eka-aluminium — boldly predicting its atomic mass, its density (about 5.9) and even its low melting point. In 1875 the French chemist Paul-Émile Lecoq de Boisbaudran found two unfamiliar violet lines in the spectrum of a zinc-blende ore from the Pyrenees and isolated the new metal by electrolysis. When Lecoq’s first density reading came out at 4.7, Mendeleev himself wrote insisting he re-measure; the corrected value, 5.9, matched the prediction and made the periodic table famous overnight. Lecoq named the element gallium after Gallia, Latin for his homeland, France.