Is Silicon a Metal?

Silicon is a close neighbor of carbon in the periodic chart. It makes up just a little over a quarter of the Earth’s crust and has the atomic number 14 and the symbol Si. It belongs to elements group 14, which are elements with four electrons in their outermost shell. It is a hard, brittle crystalline solid with a blue-gray metallic luster. It is used in various common products, ranging from ceramics and bricks to semiconductors, solar cells, computer chips, waterproofing systems, and even the creation of ferrosilicon, a popular steel alloy. But despite the glistening metallic luster, silicon is neither a metal nor a non-metal.

Understanding the Nature of Elements

Understanding the nature of elements is important for appreciating their unique properties, classification, uses, health, and environmental considerations.

The periodic chart is a table that sorts elements by their electron configuration, chemical properties, and atomic numbers. Elements are placed in rows called periods and columns called groups. Elements with similar electronic configurations like the number of particles in the outermost layers of their atoms basically form the same types of bonds. Some elements are more valuable than others, and their electron make up cannot be broken down into simple configurations.

Historical Classification of Silicon

Silicon was classified as a metal when first discovered because of its metallic luster and good heat conductivity. However, it was found to be missing some properties that make some elements metal, including ductility and malleability. Also, it was found only to conduct electricity under certain conditions. Therefore, scientists were forced to reconsider its class on the periodic table. However, the group and period remained the same because these depend on the atomic number and electron arrangement.

Where is Silicon Found in the Periodic Table?

Silicon is a member of group 14 on the periodic table. This is known as the carbon family. It is located in the row below carbon, and both have nearly the same electron makeup. In fact, the two are often confused with each other because they share various properties. However, silicon is a metalloid, while carbon is non-mental. Also, carbon is more reactive than silicon and forms many compounds.

What is a Metalloid?

Some elements of the periodic table like silicon, antimony, boron, etc are both metals and nonmetals. These elements are known as metalloids. Basically they look metallic but they exhibit the chemical behavior of non-metals. They act as metals in certain conditions and non-metals in others. For example, silicon is a non-conductor of electricity in certain states and a conductor in others. There are six generally accepted metalloids; Silicon, arsenic, boron, polonium, tellurium, and antimony. You’ll

find them in a zigzag line that separates the non-metals from the metals on the periodic chart.

Why Is Silicon a Metalloid?

Silicon is a metalloid because it has an intermediate nature. It is hard, brittle, and lustrous at room temperature, just like most metals, but it is not a good conductor of electricity under the same condition. Also, it’s not malleable and ductile like metals. It breaks easily.

Metalloid Properties of Silicon

As mentioned, silicon has an intermediate nature, which gives it metalloid characteristics. Some of its metalloid properties include:

Shiny, Metallic Luster

Silicon melts at 1410 Celsius (2570 Fahrenheit) and boils at 3265 Celsius (5859 Fahrenheit). This allows it to stay hard and lustrous at room temperature. It’s typically bluish-gray. Brittleness Silicon breaks easily like non-metals. It is not ductile and malleable but a brittle solid due to the crystal’s regular and repeating atom arrangement. 

And while the pattern strengthens it in one direction, it becomes weaker in others. It breaks easily when stressed in tension. However, brittleness is useful when the element is used to make integrated circuits. It protects transistors from damage during manufacturing.

Semiconductor Properties

Silicon conducts electricity under certain conditions only. It depends on the temperature or introduced impurities. The latter is known as doping, which involves introducing donor or acceptor impurities such as phosphorus and boron. However, conductivity can also increase with heating. Raising temperature forces the valence electrons to migrate to the conduction band, allowing the element to conduct electricity.

Chemical Reactivity

Silicon has electropositive chemical behavior. However, it is relatively inert at room temperature and only starts to react when heated, bonding readily with oxygen, halogens, and phosphorus. It can have oxidation states of +2 and +4, with the latter being the most common, and it is the state in which the element is found in most compounds.

Polymers of Silicon Include

Silanes

Basically, silanes are silicon hydrides. They are very reactive in the air and also ignite easily. They are powerful reducing agents.

Silicides

Silicides are similar to borides and carbides in structure. They are usually formed when silicon combines with more electropositive elements. The resultant chemical bonds range from conductive metal-like formations to ionic or covalent. Common silicides include CoSi2, NiSi2, FeSi2 and MoSi2.

Silica

Silica is Silicon dioxide (SiO2), the most abundant compound in the Earth’s crust, totaling about 27 % of the crust by mass. It exists in forms such as quartz, glass, sand, etc. These are typically crystalline or amorphous. As mentioned, the former is shiny and grayish, while the latter is a brownish powder. Silica is widely used to make glass, silicon chips, cement, and ceramics. It’s also used as a rubber and plastic filler.

Halides

Halides form when silicon and silicon carbides react with halogens resulting in silicon tetrahalides. Silicon tetrahalides then hydrolyze in water, forming colorless, volatile liquids. Examples of silicon halides are silicon tetrafluoride (SiF4), silicon tetrachloride (SiCl4), and silicon tetrabromide (SiBr4). They are used in various industrial applications, including manufacturing plastics, silicones, and semiconductors.

Silicic Acids

Silicic acids are hydrated silica gels formed when silicon reacts with oxygen and hydrogen. They are usually colorless weak acids that are occasionally soluble in water. Silicic acids have a crucial role in biomineralization.

Uses of Silicon

The intermediate nature of silicon makes it useful in a wide range of applications ranging from electronics to building and construction.

Silicon in Electronics

Silicon can be made to conduct electricity by raising its temperature or introducing doping agents. This makes it useful in electronic applications such as:

  • Computer chips: Silicon is used to make transistors. These are essential components of the logic gate. They allow computers to execute instructions, store data, perform computations, etc. Manufacturers benefit from the semi-conductivity and abundance properties of silicon for production of compact , cost-effective and efficient  transistors. An example is the integrated circuits; they are basically semiconductors with a number of transistors. They can be incorporated in TVs, computers, and smartphones.
  • Solar cells: These devices are useful for the conversion of natural energy into electricity. Silicon allows for the production of efficient and affordable solar cells.
  • Silicon is used to make diodes: diodes allow for the flow of current in a specific direction. Some applications of these devices are power supplies, amplifiers ,and signal processing components.
  • LEDs: you are likely to come across several LED devices in most modern homes. Their mechanism involves illumination of different intensities when there is current flow. Some LED electronics are traffic lights, flash lights, and lights used in buildings.

Silicon in Alloy Formation

Another common use of silicon is in alloy production. It has properties that allow for a reduced melting point, better brittleness, improved corrosion resistance, and an easy melting and cutting process. Some silicon alloys are:

  • Aluminum-silicon alloys. These alloys have beneficial properties like good malleability, low-density, and sturdiness. Aluminum-silicon alloys are suitable for forming processes like extrusions, castings, and forgings.
  • Copper-silicon alloys. These alloys are popular in applications like heat exchangers, electrical conductors, and roofing materials, thanks to their good-strength alloys ,good conductivity and oxidation resistance.
  • Iron-silicon alloys. Like other silicon alloys, these are also malleable, sturdy, and durable allowing for process applications with stainless steel, steel, and cast iron.

Silicon in Bricks and Ceramics

Silica, a silicon polymer, is popular with ceramics and brick manufacturers. It can withstand high temperatures without melting, making bricks and ceramics more durable, stronger, smoother, and chemical and heat resistant. Examples include silica bricks, firebricks, glazed bricks, and porcelain.

Silicon in Glass Manufacturing

Silicon is also useful in glass manufacturing. Typically, scientists melt sand to obtain silicon which is used to make glass. Silicon has a low thermal expansion; therefore, the resulting glass doesn’t change shape, volume, density, or area with temperature changes.

Is Silicon Harmful?

Silicon is generally safer in its elemental form. However, inhaling large amounts of silicon dioxide can harm the lungs. Liquid silicon is also dangerous if injected into the body. Watch out for allergic reactions too. In case of a history of allergies, talk to your doctor before working with silicon material.

Conclusion

There is a skyrocketing demand for silicon and its alloys in the electronic and construction industries. It exhibits both metallic and non-metallic properties, making it useful in these and other applications. Oushi Metal is one of the world’s top manufacturers and suppliers of silicon and silicon products. 

We produce silicon using a low-impact process and will ensure you get it in the purest form possible. Feel free to contact our team for more details and help selecting the best silicone product for your project.

 

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