Silicon: properties - uses - types

What is the element silicon?

Silicon is a chemical element with symbol (Si) found in group 14 or 4A, and period 3 of the periodic table, i.e. in the carbon family, and silicon constitutes 27.7% of the Earth's crust, and is the second most abundant element in the earth's crust After oxygen,[1] and the seventh most abundant element in the universe, silicon is classified among the metalloids, and silicon is not found free in nature, but is usually found attached to a pair of oxygen molecules such as silicon dioxide, also known as silica.[2]

Silicon properties

Silicon, like other chemical elements, has some properties that distinguish it from others, the most important of which are: [3][2]

Atomic number: 14

Mass number: 28,085 g/mol.

Physical state and colour: Solid at 20°C, with a blue-gray metallic luster.

Electrical Conductivity: Silicon is a semiconductor, and its electrical conductivity increases with increasing temperature.

Density: 2.3296 g/cm3.

Boiling point: 3265°C.

Melting point: 1414 degrees Celsius.

Isotopes: silicon-28 is the most well-known isotope, and silicon-30.

Electronic distribution: 1s2 2s2 2p6 3s2 3p2.

Silicone uses

Silicon has many uses, the most important of which are: [3][4]

1- Alloy industry: such as aluminum-silicon alloys, ferro-silicon ferro-silicon alloys, and these alloys are used in the manufacture of dynamo plates, transformers, engine blocks, cylinder heads, and machine parts, and is also used to deoxidize steel.

2- Manufacture of polymers and silicone oils: Polymers are made of silicone and oxygen bonded with methyl groups. Silicone oil is a lubricant added to some cosmetics and hair conditioners. Silicone rubber is also used as a sealant in bathrooms, around windows, pipes, and ceilings.

3- Electronics industry: High-purity silicon is used in the industries of computers, microelectronics and solar heaters, because it is a semiconductor, and silicon is impregnated with small amounts of boron, gallium, phosphorous or arsenic to control its electrical properties when manufacturing these devices.

4- Engineering and Construction Uses: Granite and most other rocks are complex silicates used in civil engineering projects. Sand consisting of silicon dioxide or silica, and clay, which is aluminum silicate, are used in the manufacture of concrete and cement. Sand is also the component The main component of glass, some silicon compounds such as silicates are found in pottery, enamels, and high-temperature ceramics.

The biological role of silicon

The presence of silicon is necessary for plant life, but its availability in animal cells is not yet certain. Plant silica (Phytoliths), which are small particles of silica, are formed inside some plants. These particles are characterized by not rotting, so their importance lies in the fact that they remain inside fossils, and their presence provides useful evolutionary evidence Silicon is classified as a non-toxic substance, but some silicates, such as asbestos, are carcinogenic, and miners and stone-cutting workers who are exposed to silica dust can develop a serious lung disease called silicosis.[3]

Silicone Compounds and Polymers

Silicon can be used in the manufacture of many polymers and compounds that are in turn used in many industries, and the most important of these polymers and compounds are the following: [4]

1. Silanes: Silanes consist of a homogeneous chain of silicon hydrates, which are very strong reducing agents, are unstable at room temperature, ignite very easily, and are highly reactive when exposed to atmospheric air.[4]

2. Silicon pesticides: Silicone pesticides have structures similar to carbides and borides, and therefore their formation temperatures are usually similar to those of the same elements found in carbides and borides.

3. Silica: Silica is also known as silicon dioxide, and silica is mainly composed of granite and sandstone.

4. Halides: Silicon halides are formed from the reaction of silicon and silicon carbides with stable halogens to form silicon tetrahalides, and these tetrasilicon tetrahalides decompose easily in water, unlike carbon tetrahalides.[4]

5. Silicate minerals: Since about 95% of Earth's rocks are composed of silicate minerals, about 28% of Earth's crust rocks and minerals are composed of silicon.[4]

6. Silicic acids: Most silica acids are found in aqueous solutions, and increasing the water concentration of these acids leads to the formation of what is known as aqueous silica gel.[4]

Types of silicone and its uses

Silicon comes under three forms, either liquid (fluids), resins, or elastomers, and they contain silicon atoms and oxygen atoms,[6] as silicon is divided into several types, which we explain as follows: Silicon Liner silicones: This type of silicone is produced through the process of analyzing and condensing the silicon dioxide compound, and this type is divided into two groups that differ in their composition, properties and uses, namely silicone rubbers and silicone resins. [5]

1. Silicone rubbers

Silicone rubber is made of silicone, carbon, oxygen and hydrogen, and is used in multiple industries such as the automobile industry, and is chemically stable and resistant to harsh conditions such as low temperatures below zero about -300 degrees Celsius. For leaks and industrial devices.[7]

Silicon elastomer is a high-performance elastomer as a synthetic rubber with multi-properties, which is characterized by high efficiency under high temperature conditions, durability, transparent color, and high electrical insulation ability.[8]

2. Silicone resins

Silicone resin is a three-dimensional, multi-chain, low-weight polymer. This type is characterized by heat stability and the required protection, which makes it best used in bonding materials such as paints and various nail coatings.[9]

This type has a tough and flexible membrane, which makes it useful for surface treatment. These types can withstand very high temperatures, which reach about 500 degrees Celsius within a short time, in addition to its excellence as a material resistant to oxidation, water and high insulation. [9]

3. Cyclic silicones

This type of silicone is produced through the hydrolysis process of the R2SiCl2 compound,[5] and this type is considered an essential type of the silicone family in addition to its safety for human use and health as well as the environment. And the gel, and after the manufacturing and consumption processes, it is noted that in the final image of the product it constitutes a small percentage of the ingredients, in addition to its entry into the manufacture of various cosmetics and deodorants.[10]

4. Silicone oils

Silicone oils are characterized by stability in temperatures and flow at large temperatures and with flexible forms, and one of the most famous manufactured types is Polydimethylsiloxane (in English: Polydimethylsiloxane), and its viscosity varies depending on the temperatures, which may reach 2,000,000 degrees Celsius.[11]

It has many properties and is characterized by strong chemical bonds between silicon and oxygen, and it spreads easily on objects due to its low surface tension in addition to its high pressure, and helps insulating greatly and resisting high stresses.[11]

Silicone Other uses

There are many areas of silicone use, depending on the conditions surrounding the medium and the function it performs, helped by its stability under high and low temperatures, and its high ability to resist water and oxygen,[6] and we explain it as follows:[5]

1.      It is used in lubricating processes under low temperatures.

2.     It is used on sites of vacuum pumps under very high temperatures.

3.     Silicon is used in industries, especially in the production of waterproof clothing.

4.     Silicon is used as an insulating material for various applications such as doors and windows.

5.     silicone is mixed with ship paint; In order to raise its efficiency under difficult weather conditions such as temperatures, humidity and any chemicals affecting the bodies.

6.     Silicone is used in the manufacture of personal care products such as deodorants, by eliminating the viscosity of perspiration in the packaging, and also in the manufacture of cosmetics, shampoos and conditioners by adding color and luster to them and raising the protection factor.[12]

7.      Silicon is used to raise the efficiency and durability of photovoltaic equipment and solar panels, due to its high tolerance under sunlight, and this reduces its cost significantly.[12]

8.     Various electronic devices, such as cameras and keyboards, are made of silicon, due to its stability and high isolation rate.[12]

9.     Silicon is used in the manufacture of wings and tanks, due to its ability to work under high temperatures and withstand stresses.[12]

Medical uses of silicone

The uses of silicon differ from the uses of silicon in the medical field, and the following are the most prominent medical uses of silicon:

1. Boosting bone mineral density

Eating foods that contain silica (silicon dioxide) promotes the health of connective tissue and bone formation, and according to a study presented by the Journal of Nutrition, Health and Aging (J Nutr Health Aging), an increase in the diet's content of silica positively affects bone mineral density in the hips area in men. and women before menopause.[13]

2. Alzheimer's treatment

Regular consumption of one liter of mineral water rich in silicon per day can reduce clinical signs of Alzheimer's disease; This is by eliminating excess aluminum levels, which are naturally linked to Alzheimer's, according to Christopher Exley, a professor at Keele University in the UK.[14]

 3. Hair strengthening

Taking 10 mg of silicon for a period of 9 months will enhance the strength of hair and prevent its breakage, and it is recommended in this regard to take vitamins and nutritional supplements that help the body retain silica; This is because this mineral does not accumulate in the body, but the latter gets rid of it with the help of the kidneys.[15]

4. Scar treatment

Silicone is used as the first line of treatment for plastic surgeons to treat scars, according to the Scientific Journal of Aesthetic Plastic Surgery, as silicone is a safe, durable, and easy-to-use material, and can be used on sensitive skin and children's skin, and it can be used either with the help of doctors or at home. [16]

Silicone gel moisturizes scars by moisturizing the top layer of the skin; which regulates the production of fibroblasts and enables the skin to breathe; The scar becomes smooth and more flat, and protects the tissue from bacteria that can increase collagen production in scar tissue, and the production of too much collagen causes the scar to appear more and change its color.[16]

5. Manufacture of medical devices and instruments

Silicon is flexible and stable, is able to withstand a wide range of temperatures, and has a high anti-rupture strength, which has encouraged its use in the manufacture of various medical devices. For example, there are surgical instrument protectors that protect the surgeon and patient from any sharp edges, isolate electrical currents and remove heat.[17]

As well as medical tubes used to deliver medicines such as peristaltic pumps, they are made of silicone, as well as face masks that are used when breathing stops during sleep and others. [17]

6. Breast filler

Many women resort to breast implants or breast fillers for various reasons, and silicone is one of the most common and safe ways to achieve this, in which silicone gel is stuffed into silicone implants, and then the latter is implanted in the breast.[18]

According to many, these implants look like normal breast tissue; This is because the silicone gel used is a thick, viscous liquid similar to natural fats in the human body.[18]

If the silicone implant ruptures, no health problems will occur, as some believe, and the rupture can be painful and can only change the shape and circumference of the breast, and here it can be removed by the surgeon and replaced with another.[18]

The importance of silicon in the electronics industry

Due to the discovered importance of silicon, the time period between the end of the twentieth century and the beginning of the twenty-first century was called the Silicon Age, where silicon played a key role in the technological development in the field of computers and electronics in that period. In addition, Santa Clara Valley was named in The United States of America is in Silicon Valley, as it is the largest gathering of companies specialized in information technology and entrepreneurship.[19]

Silicon is mainly used in the manufacture of the transistor, which is one of the most important basic components in electronics and electrical circuits. The transistor is used in the manufacture of digital processors and electronic memory cells. The transistor is considered one of the most important inventions in the twentieth century for its prominent role in the manufacture of advanced electronics. It performs a number of functions, most notably the following:[19]

1.      Switching is the connection or interruption of electrical current in an electrical circuit.

2.     Amplification is the amplification of an electrical signal.

3.     Inversion is the conversion of constant electric current (DC) into alternating current (AC).

As mentioned previously, silicon is the main component in electronics manufacturing due to its properties that distinguish it from the rest of the elements, and due to its presence in abundant quantities on the surface of the earth.

Since it is considered the second most abundant element on Earth after oxygen,[20] and because silicon is an electrically insulating or non-conductive element, a number of other elements are added to it, which are called impurities to be converted into a semiconductor So that the electric current is connected or cut off as required, and given the characteristics of silicon, it enters into each of the following industries:[19]

1.      Electrical circuits.

2.     Electronics.

3.     Digital processors.

4.     Solar cells.

5.     The glass.

6.     Various chemical industries.

References

1.      "silicon", britannica., Retrieved 4/1/2022. Edited.

2.     "silicon", livescience, Retrieved 4/1/2022. Edited.

3.     "silicon", rsc, Retrieved 4/1/2022. Edited.

4.     "uses of silicon ", byjus, Retrieved 4/1/2022. Edited.

5.     "Silcones", brainkart.com, Retrieved 11/1/2022. Edited

6.     The Editors of Encyclopaedia (30/8/2021), "silicone", britannica, Retrieved 11/1/2022.

7.      "Silicone Rubber", sciencedirect, Retrieved 11/1/2022. Edited

8.     "Silicone Rubber: Complete Guide on Highly Durable Elastomer", omnexus, Retrieved 11/1/2022. Edited

9.     "Silicone Resin", elkem, Retrieved 11/1/2022. Edited

10.  "WHAT ARE CYCLOSILOXANES?", cyclosiloxanes, Retrieved 11/1/2022. Edited ^ أ

11.     "Silicone Oils The ideal material fo thermal stability", elkem, Retrieved 11/1/2022. Edited

12.   "Silicones", chemicalsafetyfacts.org, Retrieved 11/1/2022. Edited

13.   "Silica and it's Benefits for Bone Health", get-nourished, Retrieved 13/1/2022. Edited.

14.  "Silicon-rich mineral water backed for Alzheimer’s benefits", nutraingredients, Retrieved 13/1/2022. Edited.

15.   "Silica for Hair: Can It Fight Hair Loss?", healthline, Retrieved 13/1/2022. Edited.

16.   "How Does Silicone Heal Scars?", newgelplus, Retrieved 13/1/2022. Edited.

17.   "Silicone: Expanding the Horizon for Today’s Medical Devices", medicaldesignbriefs, Retrieved 13/1/2022. Edited.

18.  "Breast implants: Saline vs. silicone", mayoclinic, Retrieved 13/1/2022. Edited.

19.   Paul Siffert, Eberhard Krimmel, Silicon: Evolution and Future of a Technology, Page 5. Edited.

20.  "Silicon", Royal Society of Chemistry, Retrieved 9/1/2022. Edited.