Gallium

Figure 1. Gallium, with atomic number 31 and atomic weight of 69.723.

Gallium is the 31^st element on the periodic table of elements. Some of its properties are listed below:

Atomic weight	69.723
Density (at 0oC)	5.91 g/cm3
Boiling point	2502 K
Melting point	302.9146 K

Gallium is a soft, light silver metal. It largely exists as a trace element in minerals and compounds. Gallium is unique in its low melting point (average human body temperature is enough to melt it) but a high boiling point.

Gallium Uses

Figure 2. Gallium sealed in vacuum ampoule.

Gallium arsenide and gallium nitride are used in red and blue/green LED lights, respectively. Both compounds are also used in semiconductors. Gallium arsenide has a molecular structure similar to silicon and can act as a substitute, particularly in electronics, and was used in the solar panels for the Mars Rover. Gallium nitride is also used Blu-ray technology, mobile phones, and pressure sensors for touch switches.

Gallium will alloy with most metals and is often used in low-melting point alloys due to its own low melting point. Gallium's high boiling point makes it useful for recording high temperatures that would normal destroy a regular thermometer, since it takes very high temperatures for gallium to reach the point of vapourisation. It is sometimes used as non-toxic substitute for mercury in regular thermometers.

Isotopes

Gallium has two isotopes found in nature:

Symbol	Natural Abundance
69Ga	60.108%
71Ga	39.892%

Video

The video below is from the University of Nottingham's periodic videos project. They have created a complete suite of short videos on every element on the periodic table of elements.

For Further Reading

• Periodic table of elements
• Metal
• Greenhouse effect
• Pollution
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