Metals and Nonmetals for (2009-2010)

Metal(s) which –

  1. Is liquid at room temperature – mercury
  2. Are most malleable – gold and silver
  3. Are poor conductors of heat – lead and mercury
  4. Can be cut with knife – sodium, potassium, lithium
  5. Is not malleable and ductile – zinc
  6. Have very low melting point – gallium and caesium
  7. Is most abundant in earth crust – aluminium
  8. React with dil HNO3- Mg and Mn
  9. Do not react with water at all – gold, silver, platinum, lead and copper
  1. React with steam only – aluminium, iron and zinc
  2. Do not react with oxygen even at high temperature – gold, platinum, silver

 

Nonmetals which –

  1. Is liquid at room temperature – bromine
  2. Are lustrous – iodine and graphite
  3. Is hardest – diamond
  4. Are good conductors of electricity – carbon and gas carbon
  5. Is most abundant in earth crust – oxygen
  6. 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.