Metals and Nonmetals for (2009-2010)

Metal(s) which – Is liquid at room temperature – mercury Are most malleable – gold and silver Are poor conductors of heat – lead and mercury Can be cut with knife – sodium, potassium, lithium Is not malleable and ductile – zinc Have very low melting point – gallium and caesium Is most abundant in earth crust – aluminium React with dil HNO3- Mg and Mn Do not react with water at all – gold, silver, platinum, lead and copper

React with steam only – aluminium, iron and zinc Do not react with oxygen even at high temperature – gold, platinum, silver

Nonmetals which – Is liquid at room temperature – bromine Are lustrous – iodine and graphite Is hardest – diamond Are good conductors of electricity – carbon and gas carbon Is most abundant in earth crust – oxygen Show allotropy – carbon, sulphur and phosphorus

 

Metal  + water(l)          metal hydroxide + H2	Metal     +    water(g)         metal oxide + H2
2K      +   H2O(l)                2KOH    +      H2	Mg         +    H2O(g)                MgO        +    H2 3Fe        +    4H2O(g)             Fe3O4    +    4H2

 

Amphoteric oxides The metal oxides which show the properties of both acidic oxides as well as basic oxides are called amphoteric oxides. They react with both acids and bases to produce salt and water.

E.g. aluminium oxide and zinc oxide

Al₂ O₃ + 6HCl 2AlCl₃ + 3H₂ O ; Al₂ O₃ + 2NaOH 2NaAlO₂ + H₂ O (Sodium aluminate)

ZnO + 2HCl ZnCl₂ + H₂ O ;

ZnO + 2NaOH Na₂ ZnO₂ + H₂ O (Sodium zincate)

Self protecting metals The metals that react with air to form a thin layer of their oxide over them to protect from further corrosion of oxidation are called self protecting metals. E.g. aluminium, zinc, magnesium, lead, etc.

Anodizing The process of forming a thick layer of aluminium oxide over aluminium metal is called anodizing. During anodizing process - a clean aluminium article is made anode and is electrolysed with dil H₂ SO₄ . The oxygen gas produced at anode reacts with aluminium to make a thicker protective layer of its oxide.

Hydrogen gas does not evolve when a metal reacts with nitric acid because nitric acid is strong oxidising agent. It oxidises the hydrogen gas produced to water and itself gets reduced to any of nitrogen oxides i.e. N₂ O, NO or NO₂ .

Aquaregia. Aquaregia is the mixture of concentrated hydrochloric acid and nitric acid in the ratio 3:1. It is called 'Royal water' because it can dissolve gold and platinum.