If you expose a new surface by cutting the silicon, that layer won't, of course, exist.Ĭhlorine dissolves in water to some extent to give a green solution. One source suggests that the lack of reactivity of silicon is due to a layer of silicon dioxide on its surface. This is probably the effect of the high surface area of the dust produced, combined with the fact that you are exposing uncontaminated silicon to the water. "The silicon is cut in a glycol slurry The powdered Si is protected somewhat from moisture in the glycol slurry, but when we clean the slurry in aqueous solutions the reaction with water takes off." Cotton and Wilkinson's Advanced Inorganic Chemistry (third edition - page 316) suggests that the reactivity of one of these could be due to a very high surface area, or perhaps because the silicon exists in a graphite-like structure.Ī correspondent from the silicon industry tells me that when silicon is cut into slices, the silicon dust formed reacts with water at room temperature - producing hydrogen and getting very hot. Note: These more reactive forms are produced as powders. Most sources suggest that this form of silicon will react with steam at red heat to produce silicon dioxide and hydrogen.īut it is also possible to make much more reactive forms of silicon which will react with cold water to give the same products. The common shiny grey lumps of silicon with a rather metal-like appearance are fairly unreactive. The truth seems to depend on the precise form of silicon you are using. There is a fair amount of disagreement in the books and on the web about what silicon does with water or steam. The reaction is relatively slow because of the existing strong aluminium oxide layer on the metal, and the build-up of even more oxide during the reaction. Hydroxides are only ever produced using liquid water.Īluminium powder heated in steam produces hydrogen and aluminium oxide. Notice also that the oxide is produced on heating in steam. That leaves dark grey products (including silicon and perhaps boron from the glass) as well as the white magnesium oxide. Note: If you are heating the magnesium in a glass tube, the magnesium also reacts with the glass. Magnesium burns in steam with its typical white flame to produce white magnesium oxide and hydrogen. Magnesium hydroxide is formed as a very thin layer on the magnesium and this tends to stop the reaction. Magnesium has a very slight reaction with cold water, but burns in steam.Ī very clean coil of magnesium dropped into cold water eventually gets covered in small bubbles of hydrogen which float it to the surface. Sodium has a very exothermic reaction with cold water producing hydrogen and a colourless solution of sodium hydroxide. This page describes the reactions of the Period 3 elements from sodium to argon with water, oxygen and chlorine. CHEMICAL REACTIONS OF THE PERIOD 3 ELEMENTS
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