Non Metals

In this chapter, we discuss about non-metals like silicon, sulphur, and their properties and uses in Grade 8 Science. Reference Notes for Grade 8.

Non-Metals

Non-metals are the elements in groups 14-16 of the periodic table. Non-metals are the bad conductor of electricity or heat. As opposed to metals, non-metallic elements are very brittle and cannot be rolled into wires or pounded into sheets. Non-metals have low melting and boiling points.

Silicon

Silicon is not found in the pure state. Silicon is the most abundant electropositive element in the earth’s crust. It’s a metalloid with a marked metallic lustre and very brittle. Some important ores of silicon are:

• Silica
• Feldspar
• Kaolinite
• Mica

Properties of silicon are as follows:

• It is grey solid non-metal.
• It is found in both crystalline and amorphous formed.
• It is a weak electrolyte in crystalline form but strong electrolyte in amorphous form.
• It doesn't react with air, water and acid.

Uses of silicon are as follows:

• It is used to make glasses.
• It is used to make the clay pot.
• It is used to make statue and buildings.
• Silicon chip is used to make semiconductors.
• It is used to make polish and paints.

Sulphur

Sulphur is a chemical element with symbol S and atomic number 16. It is an abundant, multivalent non-metal. Some important ores of sulphur are:

• Dolomite
• Gypsum
• Calcite
• Quartz
• Pyrite

Properties

• Sulphur is found in both crystalline and amorphous form.
• It is not soluble in water.
• It is the bad conductor of heat and electricity.
• Sulphur dioxide is formed when sulphur is burnt in the presence of air.
• It doesn't react easily with acid.

Uses

• Milk of sulphur is used in medicine.
• Sulphur is used in the manufacture of matches, gunpowder etc.
• It is also used as disinfectant.
• It is also used in the vulcanization of rubber.