6.3 SILICON COMPOUNDS
6.3 SILICON COMPOUNDS second most abundant element in the earth
crust non- metal does not exist as free element, combined with
other element to form silicon compounds. silicon compounds can be
divided into 2 forms :Silicon + oxygen = Silica or silicon dioxide
Ex : sand, sandstone, flint, quartz, gemstoneSilicon + oxygen +
metal = Silicates Ex : Silicon + oxygen + sodium = sodium silicates
Ex : clay, asbestos, mica, feldspar, topaz, ruby and jade
1The stability of silica and silicates can be determined by
testing their properties :a. solubility in waterb. reaction with
dilute hydrochloric acidc. effects on heat
2SILICA/ SILICATESSOLUBILITY IN WATERREACTION WITH DILUTE
HYDROCHLORIC ACIDEFFECT OF HEATSANDINSOLUBLENO REACTIONITS FORM
DOES NOT CHANGEQUARTZINSOLUBLENO REACTION
ITS FORM DOES NOT CHANGE
ASBESTOSINSOLUBLE
NO REACTION
ITS FORM DOES NOT CHANGE
MICAINSOLUBLE
NO REACTION
ITS FORM DOES NOT CHANGE
3Are silica and silicates more stable than oxides, sulphides and
carbonates?Yes, because they are a. insoluble in water, except for
sodium silicateb. do not react with dilute acidsc. do not change
its form when heated
4Uses of silicon compounds in everyday lifeVery stable, many
uses in various industriesElectronic chips, glass, optical fibres ,
ceramics and porcelainQuartz- make glass and ceramicsMica- used as
insulator in microwave oven, car engines and electric
ironAsbestos-fire insulator, electrical insulators and fireproof
materialsTopaz, ruby, jade jewelleries 5
