Metals and Non-metals Test - 11

Bromine is a non-metal. Copper is less reactive than hydrogen. Potassium is the most reactive while gold is the least reactive.

Magnetic separation is used for the concentration of iron-ore. Froth floatation method is used for removing gangue from sulphide ores. Leaching is used where an ore such as bauxite is soluble in a suitable solvent like NaOH. Gravity method is based on difference in densities.

Highly reactive metals like sodium, which cannot be obtained be extracted by reducing their oxides with carbon, are obtained by electrolysis of their chlorides (electrolytic reduction) in molten state. Electrolytic refining is used for refining impure copper. Zinc oxide can be reduced with carbon (or coke). Chromium can be obtained from its oxide ore by reduction with aluminium powder.

Most metals form basic oxides. Non-metals form acidic oxides. Amphoteric substances like zinc and aluminium form basic oxides as well as acidic oxides. Most salts are neutral in nature.

Calcium reacts with cold water (less violently as compared to the reaction of sodium with water) to form calcium hydroxide and hydrogen gas. Bubbles of hydrogen gas formed during the reaction stick to the surface of calcium and calcium pieces start floating in the water.

Highly reactive metals like Potassium, Sodium (Na), Calcium (Ca), Aluminium and Magnesium are obtained by electrolysis of their chlorides in molten state. They cannot be extracted by reducing their oxides with carbon. Iron (Fe) can be obtained from its oxide ore by reduction with coke or aluminium powder. Copper (Cu) can be obtained by heating its sulphide ore in air.

Metals exhibit electrical conductivity (due to free electrons), sonority (production of ringing sound when struck) and ductility (ability to be drawn into wires).

Carbon is a tetravalent element and does not lose or gain electrons easily to form electrovalent bonds. It forms covalent bonds with other elements.

An acidic oxide will turn blue litmus red. Non-metal oxides (Oxides of S and N) are acidic in nature. Metal oxides (Oxides of Mg and Na) are basic in nature.

Metals are alloyed to improve the properties of metals. An alloy is a homogeneous mixture of two or more metals. They are stronger, harder and more resistant to corrosion. They have a lower melting point and lower thermal conductivity than that of the constituent metals.