Gallium

Gallium is a chemical element with an atomic mass of 69.72 g.mol-1. The atomic number of gallium is 31. Gallium is generally considered to be a soft metal at standard pressure and temperature. The Gallium symbol is Ga.

How was Gallium Discovered?

Dmitri Mendeleev’s periodic law described how each chemical element was related to each other. The periodic table he set up had empty places in the table. The place for number 31 was also empty. On the basis of the elements on the side of the box for element number 31, Mendeleev was certain that element number 31 did exist but was just not found. He even went a step ahead and predicted the characteristics of the to-be-found element and named the element “eka-aluminium”.

The chemical element was soon found by a French chemist named Paul Emile Lecoq de Boisbaudran in the 1870s. Paul was determined to discover the element between Aluminum and Indium. Since Zinc had an atomic number 30, Paul believed that Gallium could be found in Zinc’s Ore. He decided to study the spectra (distinct lines produced by chemical elements when heated) that the ore produced. To his surprise and luck, the metal he was searching for was found in the ore but in traces. Later he was able to produce a good amount of pure gallium. He assigned the name “gallium” to give tribute to France’s old name-Gallia.

Physical Properties of Gallium 

• Gallium is a soft metal with a very shiny surface. Pure gallium has a silver-blue kind of colour. The elemental or natural form of gallium is not found in nature. It has to be extracted through smelting or other means. It is hugely different and therefore, not very metal-like. It is soft and can be cut with a knife. 

• Its melting point is at around 29 degrees Celsius, which is pretty low. Therefore, if your body temperature is above 30 degrees Celsius, a part of it can easily melt in your hands. It is one of the four non-radioactive chemical elements (Mercury, rubidium, and caesium) that are liquid at room temperature. Gallium sticks to glass or porcelain very easily.

• Another interesting feature of the Ga element is that it can supercool. Supercooling is a chemical phenomenon where a substance can cool without solidifying itself below its freezing point. Since the melting point for Gallium is around 29 degrees Celsius, it is probable that it will start to become a solid below 29 degrees. But this is not the case for Gallium. It can supercool itself without becoming a solid and retaining its liquid-like structure. Gallium does not crystallise easily either. 

• Gallium also has alloying properties that make it easy to alloy with metals like Aluminum and Zinc. It can easily diffuse in the metal boundaries of Zinc, aluminium and steel. One famous gallium alloy is called the Galinstan that consists of gallium, tin and indium. 

• The boiling point for Gallium stands at approximately 2200 degrees Celsius, and its density is 5.907 grams per cubic centimetre which is high like the density of water. It is the only element to have such a great ratio between its melting and boiling point.

Isotopes of Gallium

In an amazingly simple way, isotopes are atoms with the same atomic but different atomic mass. The difference is caused due to the presence of more neutrons. Isotopes are chemically similar, but there exist physical differences. Gallium has as many as 25 known isotopes. Out of these, only two are stable- Gallium 69 and Gallium 71. The former one is most abundant and makes for most of its natural presence. There also exists some radioactive isotopes (isotopes that emit radioactive radiations) of Gallium like the most famous one- Gallium 67.

From the above information, we can deduce that the physical properties of Gallium are highly dependent on the temperature factor. 

Gallium Properties in Terms of Chemistry

Gallium is a fairly reactive chemical element. It is not highly reactive like alkali metals. Out of the four non-radioactive metals that are in their liquid forms in room temperature (Mercury, Caesium, and Rubidium), gallium is the only element which is not highly reactive like Caesium and Rubidium or highly toxic like Mercury.

It is relatively stable in water and air, but Gallium reacts with alkaline as well as acid. 

Gallium Uses

• Pure gallium is used in the semiconductor industry. They are used in making integrated circuits and electronic chips. Gallium compounds are also used in laser devices. It is abundantly used in making LEDs. 

• Since Gallium is a liquid metal at room temperature, it is used just like Mercury used in medical thermometers. 

• Gallium alloys easily with metals. Some of the gallium alloys act as substitutes for toxic mercury alloys.

• Gallium wets glasses and sticks to them easily. This helps in making great mirrors.

• An alloy of gallium is also used to stabilise the plutonium used in nuclear devices. Another application of the alloys of gallium is its usage to cool down machines and other electronic devices like the computer.

• Gallium is heavily used in the biomedical industry. Several Gallium salts are used in medical treatments. Some compounds show anti-cancerous properties as well. Research studies are being conducted to produce gallium involving treatments for inflammation, cancer, and other such diseases.