The chemical element of galium practically does not occur in nature in its free form. It exists in admixtures of minerals, from which it is rather difficult to separate. Galium is considered a rare substance, some of its properties are not fully understood. Nevertheless, it is used in medicine and electronics. What is this element? What properties does it possess?
Galium - metal or non-metal?
In the periodic system, an element belongs to the thirteenth group of the fourth period. It is named after the historical region - Gaul, of which France was a part - the birthplace of the discoverer of the element. The symbol Ga is used to denote it.
Galium is included in the group of light metals along with aluminum, indium, germanium, tin, antimony and other elements. As a simple substance, it is fragile and soft, has a silver-white color with a slight bluish tint.
Discovery story
Mendeleev “predicted” Galium, leaving a place for him in the third group of the periodic table (according to an outdated system). He roughly called its atomic mass and even predicted that the element would be discovered spectroscopically.
A few years later, the metal was discovered by the Frenchman Paul Emile Lecock. In August 1875, a scientist studied the spectrum of the sphalerite mineral from a deposit in the Pyrenees and noticed new purple lines. The element was called galium. Its content in the mineral was extremely small and Lekok managed to isolate only 0.1 grams. The discovery of the metal was one of the confirmations of the correctness of Mendeleev’s prediction.
Physical properties
Galium metal is very ductile and fusible. At low temperatures, it is in a solid state. To turn it into a liquid, a temperature of 29.76 degrees Celsius or 302.93 Calvin is enough. You can melt it by holding it in your hand or dropping it in a hot liquid. Too high temperatures make it very aggressive: at 500 degrees Celsius and above it can corrode other metals.
The crystal lattice of galium is formed by diatomic molecules. They are very stable, but weakly interconnected. To break their connection, you need a very small amount of energy, so galium easily becomes liquid. In fusibility, it is five times superior to indium.
In the liquid state, the metal is denser and heavier than in the solid state. In addition, he conducts electricity better. Under normal conditions, its density is 5.91 g / cm³. Boils metal at –2230 degrees Celsius. When hardened, it expands to approximately 3.2%.
Chemical properties
In many chemical properties, galium is similar to aluminum, but exhibits less activity and reactions with it proceed more slowly. It does not react with air, instantly forming an oxide film, which prevents its oxidation. It does not react to hydrogen, boron, silicon, nitrogen and carbon.
Metal perfectly interacts with almost any halogen. It only reacts with iodine when heated, reacts with chlorine and bromine even at room temperature. In hot water, it begins to displace hydrogen, forms minerals with mineral acids and also releases hydrogen.
With other metals, galium is able to create amalgams. If liquid galium is dripped onto a solid piece of aluminum, it will begin to penetrate into it. By invading the crystal lattice of aluminum, the liquid substance will make it brittle. In just a few days, a solid metal bar can be crushed with your hands without much effort.
Application
In medicine, galium metal is used to fight tumors and hypercalcemia, and is also suitable for the radioisotope diagnosis of bone cancer. However, preparations containing the substance can cause side effects, such as nausea and vomiting.
Galium metal is also used in superfrequency electronics. It is used for the manufacture of semiconductors and LEDs, as a piezoelectric material. From an alloy of gallium with scandium or nickel, metal adhesives are obtained. In an alloy with plutonium, it plays the role of a stabilizer and is used in nuclear bombs.
Glasses with this metal have a high refractive index of the rays, and its oxide Ga 2 O 3 allows the glass to transmit infrared rays. Pure galium can be used to make simple mirrors, as it reflects light well.
Prevalence and deposits of Galium
Where to get galium? Metal can easily be ordered online. Its cost ranges from 115 to 360 dollars per kilogram. The metal is considered rare, it is very dispersed in the earth's crust and practically does not form its own minerals. Since 1956, all three of them were found.
Often, galium is found in zinc, iron, and aluminum ores. Its impurities are found in coal, beryl, pomegranate, magnetite, tourmaline, feldspar, chlorites and other minerals. On average, its content in nature is about 19 g / t.
Most of all, galium is contained in substances that are close to it in composition. Because of this, it is difficult and expensive to extract from them. Its own metal mineral is called gallite with the formula CuGaS 2 . It also contains copper and sulfur.
Human impact
Little is known about the biological role of metal and its effect on the human body. In the periodic table, it is located next to the elements that are vital for us (aluminum, iron, zinc, chromium). There is an opinion that as an ultramicroelement, galium is part of the blood, accelerating its flow and preventing the formation of blood clots.
One way or another, a small amount of the substance is contained in the human body (10 -6 - 10 -5 %). Galium enters it along with water and agricultural food. It lingers in bone and liver.
Galium metal is considered to be low toxic or conditionally toxic. In contact with the skin, small particles remain on it. It looks like a gray dirty stain that is easy to clean with water. The substance does not leave burns, but in some cases can cause dermatitis. It is known that a high content of galium in the body causes disturbances in the liver, kidneys and nervous system, but this requires a very large amount of metal.