This PSEB 8th Class Science Notes Chapter 4 Materials: Metals and Non-Metals will help you in revision during exams.
PSEB 8th Class Science Notes Chapter 4 Materials: Metals and Non-Metals
→ Materials can either be metals or non-metals.
→ Metals differ from non-metals in physical and chemical properties.
→ All metals share certain physical and chemical properties.
→ Metals are usually shiny, hard, sonorous, malleable, and ductile.
→ They conduct heat and electricity.
→ They are solids at room temperature with the exception of mercury which is liquid.
→ They have high melting points.
→ Non-metals exhibit a dull luster.
→ They are poor conductors of heat and electricity, non-sonorus, and are brittle.
→ They exist as solids, liquids, or gases at room temperature.
→ They have low melting points.
→ Metals usually combine with oxygen to form basic oxides.
→ Non-metals usually combine with oxygen to form acidic oxides.
→ Rust is formed by the action of water and air on iron.
→ Some metals react with water. Sodium reacts vigorously even with cold water forming sodium hydroxide and hydrogen. Gold does not react even with steam.
→ Sodium is stored in kerosene oil.
→ Phosphorus is kept in water as it reacts vigorously with air.
→ Non-metals do not react with water.
→ Some metals react with acids (hydrochloric acid) and replace hydrogen atoms in their molecules.
→ Gold, copper, and silver are unaffected by hydrochloric acid.
→ Metals in their increasing order of reactivity with oxygen, water, and acid are Gold, Silver, Copper, Iron, Zinc, Aluminium, Magnesium, and Sodium.
→ More reactive metals replace less reactive metals from their compounds.
→ Hydrogen gas burns with a pop sound.
→ Metals have wide use in industry, kitchen, household items transport, etc.
→ Non-metals are also widely used.
→ Oxygen is essential for life sustenance.
→ Nitrogen is used in fertilizer and crackers.
→ Iron, Magnesium, Sodium, etc. are needed by the human body.
→ Malleability: The property by which metals can be hammered/beaten into sheets.
→ Ductility: The property by which metals can be drawn into wires.
→ Sonorus: The property of metals to give a ringing (tinkling) sound when struck.
→ Lustre: The property of materials having a shining appearance.
→ Conductance: The property by which heat or electricity can be transferred from one end of a metal to another end.
→ Acidic Oxides: The oxides of non-metals are acidic oxides as they dissolve in water to give acids.
→ Basic Oxides: The oxides of metal the basic in nature as they form bases on the addition of water.