Silicon
At number 14 is the unusual element Silicon with the chemical symbol Si. Why do I say it is any more unusual than the others? Well with its 4 outer shell electrons, it sits in the periodic table just under Carbon. We already learned that carbon is a non-metal. We have also learned that the elements with the same number of outer shell electrons behave similarly. When it comes to Silicon however this is not quite true. Silicon has some properties of a metal and some of a non-metal posing problems for scientists as to which group it should be in. In the end they decided it should go into a group called metaloids - a material with some metal and some non-metal characteristics. We also found out a few weeks ago that Boron has this same part metal, part non-metal behaviour.
This nearly metal behaviour is what makes Silicon interesting and very important to our lives today. It is known as a semiconductor because it doesn't conduct electricity as well as a metal but it is better at conducting than a non-metal. Semiconductors are widely used in the electronics and computer industries.
So what is it like? Well, Silicon is grey with a metallic appearance. It is very plentiful in the universe, but is hardly ever found as elemental Silicon. Instead it is found combined with oxygen as silica, SiO2. Sand is made of silica and this sand is in turn used to make glass. Small bags of Silica are also often found packed with shoes or in new handbags. The job of these little packets is to absord water so the leather products don't get damp.
Pure crystalline Silicon dioxide resonates at a certain frequency and because of this property it is used in watches.
Silicon combines with carbon oxygen and hydrogen to make a series of polymers known as silicones. You might have come across such rubbery polymers - the wristbands which were very popular a few years ago were made from silicone..
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