Silicon Presentation

Slide 1

I am going to talk to you about Silicon. As you can see Silicon sits next to aluminium and below carbon in the periodic table.

Slide 2

If we all think on what we know about silicon for a minute, some of us may recognize silicon as being the key part of sand. Others may think of computer chips; and there is no doubt a few of you will think of breast implants.

I’m not going to focus on sand or surgery, but the influence that silicon has had on our everyday lives, you may not realise it but because of its semi conducting properties after doping, silicon is responsible for the revolution in electrical devices from the first transistor radios to the tiny mobile phones of today. In fact, without the invention of the transistor, I would not be able to do this presentation as computers and such electrical devices would have to be many times larger and a lot less powerful and also very expensive.

Silicon is a , or . It rarely occurs in basic element form, virtually all of it existing as compounds. Silicon is best known in two forms:

  1. A dark brown, powdery amorphous form, which is best known for its presence as beach sand.

  1. A grey, metallic-looking crystalline form, which is best known for its impact upon modern civilization - as the foundation material for electronic semiconductor components.

Talk about Silicon picture on board (crystalline type) 

Slide 3

Here are the contents of my presentation. 

Slide 4

Carbon, silicon and germanium (germanium, like silicon, is also a semiconductor) have a unique property in their electron structure -- each has four electrons in its outer orbital. This allows them to form nice crystals. The four electrons form perfect covalent bonds with four neighbouring , creating a lattice. In carbon, we know the crystalline form as . In silicon, the crystalline form is a silvery, metallic-looking substance.

Metals tend to be good conductors of electricity because they usually have "free electrons" that can move easily between atoms, and electricity involves the flow of electrons. While silicon crystals look metallic, they are not, in fact, metals. All of the outer electrons in a silicon crystal are involved in perfect covalent bonds, so they can't move around. A pure silicon crystal is nearly an insulator -- very little electricity will flow through it.

Slide 5

As you can see from the square, Silicon is the  in the  that has the symbol Si and  14. Silicon is less reactive than its chemical analog . It is the second most abundant element in the 's crust, being second only to oxygen. It makes up 25.7% of it by weight. It occurs in , , ,  and , mainly in the form of  (also known as silica) and  (compounds containing silicon, oxygen and metals). Silicon is the principal component of , , , most  devices, and , the latter a plastic substance often confused with silicon.

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Pure silicon crystals are rarely found in nature, as natural silicon is usually found as  (SiO2). Pure silicon crystals can be found as inclusions in , or in volcanic exhalations.

In America regular grade silicon (99%) costs about $0.50/g. Silicon 99.9% pure costs about $50/lb; hyper pure silicon may cost as much as $100/oz.

Miners, stonecutters, and others engaged in work where siliceous dust is breathed into large quantities often develop a serious lung disease known as silicosis.

Explain table 

Atomic Radius: A measure of the size of an atom, assuming the atom has the shape of ...

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