Gallium: Metal That Melts In Your Hands
Gallium is a fascinating metal with a low melting point of about 29.76°C (85.57°F), which means it can melt in the warmth of your hand, transforming from a solid, silvery metal into a liquid puddle due to human body heat.
What is Gallium
Gallium is a soft, silvery metal that is in the post-transition metals category on the periodic table, symbolized by Ga with an atomic number of 31. It is not found in its free elemental form in nature, but rather as a trace element in various minerals like bauxite and sphalerite. Gallium can be extracted as a byproduct during the refining of other metals, such as aluminum and zinc.
Gallium shares the higher-density liquid state with a short list of other materials that includes water, silicon, germanium, antimony, bismuth, and plutonium.
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A hand holding a small piece of gallium metal, which is melting due to the warmth of the hand. |
The melting point of gallium, at 302.9146 K (29.7646 °C, 85.5763 °F), is just above room temperature, and is approximately the same as the average summer daytime temperatures in Earth's mid-latitudes.
The melting point of gallium allows it to melt in the human hand, and then refreeze if removed. The liquid metal has a strong tendency to supercool below its melting point/freezing point.
Properties of Gallium
Appearance: Silvery-blue metallic solid.
Melting Point: 29.76 °C (85.57 °F) - it can melt in your hand.
Boiling Point: 2,204 °C (3,999 °F).
Density: 5.91 grams per cubic centimeter at room temperature.
Hardness: Soft enough to be cut with a knife.
Thermal Expansion: Gallium expands when it solidifies, unlike most metals.
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Liquid gallium, a silvery-white metal with a low melting point, appearing almost like mercury. |
Chemical Properties of Gallium
Reactivity with Acids and Alkalis: Gallium reacts with both acids and alkalis, forming gallium salts. It is amphoteric, meaning it can react with acids and bases alike.
Oxidation States: The common oxidation states of gallium are +3 and +1, with the +3 state being more stable.
Reaction with Air: Gallium does not react rapidly with oxygen in the air at room temperature. It forms a protective oxide layer that prevents further oxidation.
Solubility: Gallium is insoluble in water but dissolves in hydrochloric acid, forming gallium chloride.
Gallium is one of the four non-radioactive metals (along with caesium, rubidium, and mercury) that are liquid at or near typical room temperatures. Of these, gallium is unique for being neither highly reactive like rubidium and caesium, nor highly toxic like mercury, making it suitable for use in metal-in-glass high-temperature thermometers.
Gallium does not crystallize in any of the simple crystal structures. The stable phase under normal conditions is orthorhombic with 8 atoms in the conventional unit cell. Within a unit cell, each atom has only one nearest neighbor (at a distance of 244 pm).Gallium does not exist as a free element in the Earth's crust, and the few high-content minerals, such as gallite (CuGaS2), are too rare to serve as a primary source.
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Gallium metal, a unique element, can change its state from solid to liquid and back again at relatively low temperatures. |
Uses of Gallium
Semiconductors and Electronics: Gallium is widely used in the production of semiconductors, such as gallium arsenide (GaAs) and gallium nitride (GaN), which are crucial for making light-emitting diodes (LEDs), solar panels, and high-speed electronics.
Thermometers and Thermostats: Gallium has a low melting point (around 29.76 °C or 85.57 °F), allowing it to be used in high-temperature thermometers as a non-toxic alternative to mercury.
Medical Applications: Gallium isotopes are used in medical imaging and as a therapeutic agent to treat certain cancers and inflammatory conditions.
Alloys: Gallium is used to create low-melting-point alloys, such as galinstan (gallium, indium, and tin), which are used in thermometers and cooling systems.
Solar Cells: Gallium arsenide-based solar cells are used in space applications due to their high efficiency and durability.
LEDs and Laser Diodes: Gallium compounds are crucial for producing blue and violet LEDs, laser diodes, and other optoelectronic devices.
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| Gallium (Ga) Metal. |
Facts About Gallium
Amphoteric Nature: Can act as both an acid and a base in reactions.
Discovery: It was discovered by the French chemist Paul-Émile Lecoq de Boisbaudran in 1875 through spectroscopy.
Named After France: The name "Gallium" comes from the Latin word "Gallia," meaning France.
Non-toxic and Non-hazardous Metal: Unlike other metals like mercury, gallium is non-toxic, though it can stain the skin.
Supercooling Property: Gallium can remain in the liquid state below its freezing point if cooled carefully, a property known as supercooling.
How To Melt Gallium: Simply place the piece of gallium in the palm of your hand and let the warmth of your body heat do the work!
Gallium's unique properties and versatility make it valuable in various high-tech industries, from electronics to medicine.