Gallium | Chemistry Notes

Gallium is one of the most interesting metals that exist on the surface of the Earth. It is a non-toxic, glass-like soft metal having a melting point slightly above room temperature. So if you hold it in the palm of your hand, it will melt and will solidify, once it is set down.

Gallium forms 0.0019 percent of Earth's crust and found in traces. The gallium can be extracted through smelting, as a byproduct of aluminum and zinc production.

In the Periodic table, it is placed between metals and metalloids and grouped in the Boron family (Group 13). So it is known as a post-transition metal / poor metal, having poor conductivity and being brittle.


  • Atomic no. – 31.
  • Atomic symbol – Ga.
  • Atomic weight – 69.723.
  • Density – 5.91 g / cm³.
  • Boiling point – 2204 °C.
  • Melting point – 29.76 °C.
  • Electronegativity – 1.81.
  • Phase at room temperature – Solid.
  • Color – Silver (in purest form) & blue-gray (in solid state).
  • No. of isotopes – 24 (whose half-lives are known).
    • Common isotopes – Ga-69  & Ga-71 (stable isotopes).
  • Largest Producers – Australia, France, Germany & Russia.


It was Dmitri Mendeleev, the inventor of Periodic table who predicted the existence of aluminum type metal in 1869 and named it "eka-aluminum" (Sanskrit word for "beyond"). He left the 31st of the periodic table box empty for he believed his prediction was correct.

Six years later in 1875, a French man named Paul-Émile Lecoq de Boisbaudran discovered Gallium, when he spotted a line in the violet part of the visible spectrum at 417nm in a sample of Sphalerite (a zinc sulfide mineral).

The origin of the name "Gallium" comes from the Latin word "Gallia," which means France.

Interesting Facts

  • It can be supercooled quite easily.
  • When Gallium is applied to glass, it turns into a mirror.
  • The greatest ratio between melting point and boiling point of any element.
  • Liquid gallium can't be kept in glass or metal containers because when it freezes, it expands to 3.1 percent of its original volume.


  • Used to make low-melting alloys.
  • Used in nuclear bombs to stabilize the crystal structure.
  • Gallium trichloride is used to study solar neutrinos produced in the sun. 
  • Heavily used in the electronics industry (especially Gallium arsenide & Gallium nitride).
    • Gallium nitride – Blu-ray technology, mobile phones & pressure sensors.
    • Gallium arsenide – Semiconductors, microwave, and infrared circuits, solar panels & LEDs.
  • Used in thermometers, barometers, heating and cooling devices, heat transfer systems, etc.
  • The radioactive isotope of Gallium, Ga-67 is employed in gallium scan (Ga scintigraphy), a diagnostic test in the medical field for detecting cancers and tumors.
  • Gallium nitrate is used in the treatment of hypercalcemia (where the calcium in the blood is higher than the normal levels, due to overactive parathyroid glands).
Gallium arsenide with its capability of converting electricity directly into coherent light is nowadays touted as the best alternative for silicon, as it is more efficient than silicon.


  • Atomic number – Number of protons present in the nucleus.
  • Atomic weight – Average mass of the atom.
  • Isotopes – Atoms of the same element with a different number of neutrons.
  • Supercooling – The process in which a substance is cooled below its freezing point without turning it into a solid. 
  • 4 metals that exist as a liquid at room temperature – Gallium, Mercury, Caesium & Rubidium.
  • Only non-metal that exists as a liquid at room temperature – Bromine.