Silicon (Si) - the second richest element in the earth's crust

Today's video focuses on a very common non-metallic element - silicon. It is a carbon group element in the third period of the periodic table.

In 1811, French chemists first obtained impure amorphous silicon by heating potassium and silicon tetrafluoride, which can be obtained in a variety of ways. In the crust, it is the second most abundant element, which makes up 26.4 percent of the total mass of the crust, is second only to oxygen.

Silicon, usually in the form of complex silicates or silica, is found in rocks, gravel and dust. Pure silicon has amorphous silicon and crystalline silicon allotropes. Gray, shiny crystalline silicon looks more like a metal than black amorphous silicon. Silicon is insoluble in water and ordinary inorganic acids, such as nitric, hydrochloric, and sulfuric; It's soluble in hydrofluoric acid and alkali solutions.

The simplest way to make silicon is to heat a mixture of silica sand and magnesium powder. Heating up a small portion of the tube containing the mixture, when the temperature reaches, you will see that the reaction will immediately begin, emitting high temperatures, white smoke and dazzling white light; In this phenomenon, two reactions occur simultaneously, silica and magnesium react to form magnesium silicide and amorphous silicon. In this reaction, magnesium reacts not only with sand, but also with glass tubes, which also contain silica. That's why the tubes are destroyed, not just because of the high temperatures. If you break the test tube, you can see the product; Dark brown dust is amorphous silicon. And when you pour this stuff into dilute hydrochloric acid, you will see something very interesting which is the magnesium silicide reacted from the previous reaction with hydrochloric acid. And it immediately reacts with oxygen, that's why we saw the spark. Silane and methane are formulated in a similar way, with silicon atoms instead of carbon atoms. Unlike methane, methane needs to ignite before it can react with oxygen to start burning while Silane can start burning with oxygen on its own.

Another interesting experiment is to make silica gel. When dilute hydrochloric acid is added to a solution of sodium silicate, commonly known as sodium silicate, a jelly-like gel is formed after a period of time. However, if you add concentrated hydrochloric acid, you won’t get a gel, and the resulting solution is in a sol state and can still flow. But when you heat the solution, it ends up as a silicone gel.

It's still sodium silicate, and if you add a little bit of ferric chloride, you can see the product grow like a living seaweed. Everyone can try it at home and see what your algae look like. You can also substitute calcium, magnesium, copper, nickel, cobalt, barium, zinc, chromium and manganese salts for ferric chloride.

Nowadays, silicon can be found everywhere in people's life. The main component of glass is silicate compound salt, and silicon is also found in cement. High purity monocrystalline silicon is an important semiconductor material, widely used in diodes, transistors, thyristors and various integrated circuits. The chips and cpus inside computers are made of silicon. High transparency glass fiber can be produced from pure silica, which is widely used in optical fiber communication.

Silicon is one of the essential trace elements in human body, which is necessary in the formation of connective tissue and cartilage. Silicon is also a component of collagen.