Metals & Non-Metals class 10 science..

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CHEMICAL PROPERTIES OF METALS:

1. Reaction of Metals with oxygen present in Air:  

Most of the metals react with oxygen to give metal oxides.
      Metal  +  oxygen  ➡  Metal oxide.

• Reaction of highly reactive metals such as sodium, pottasium & lithium with oxygen:
Sodium, pottasium & lithium are highly reactive metals. These metals react with oxygen present in Air, even at room temperature.
           4Na  +  O2   ➡  2Na2O
            4K   +  O2   ➡  2K2O
            4 Li  +  O2   ➡   2Li2O
Sodium, potassium & lithium are stored in kerosene oil in order to protect them from atmospheric moisture & oxygen.

• Reaction of less reactive metals like magnesium, aluminum & zinc with oxygen:  Magnesium reacts with oxygen in Air at its ignition temperature to form Magnesium oxide which is a white powder. Magnesium wire burns in oxygen with dazzling white light. Ignition temperature is lowest temperature at which a substance catches fire.
          2 Mg  +  O2  ➡    2MgO

• Reaction of iron with oxygen:  Iron does not burn in Air even on strong heating but begins to glow with a bright light. At high temperature, it combines with oxygen of the air to form iron oxide. 

• Reaction of copper with oxygen:  Copper does not burn in Air even on strong heating.  on heating for long time, the outer surface of the copper metal reacts with oxygen to form black coloured copper.

• Reaction of noble metals like silver, gold & platinum with oxygen:  Noble metals such as silver, gold & platinum do not react with oxygen, even on prolonged heating.

2. Reaction of Metals with water:  

Metals react with water under different conditions to form a metal hydroxide or a metal oxide along with evolution of hydrogen gas.
Metal + water ➡ Metal hydroxide + Hydrogen gas

• Reaction of reactive metals sodium & potassium with water:  Reactive metals such as sodium & potassium react very violently with even ice- cold water form corresponding hydroxides with the evolution of hydrogen gas.

               2Na +  2H2O  ➡  2NaOH + H2
• Reaction of calcium with water:  Calcium also reacts with cold water at room temperature to form calcium hydroxide & hydrogen gas. 
  Ca + 2H2O ➡ Ca( OH)2  + H2 + small amount of heat energy.

• Reaction of magnesium with water:  Magnesium is much less reactive than calcium in its reaction with water. It does not react with cold water. It reacts only with hot water to form Magnesium hydroxide & hydrogen gas.

           Mg + 2H2O ➡ Mg(OH)2 + H2

• Reaction of aluminium,zinc & iron with water:
 Metals like aluminium, iron, & zinc are even less reactive than magnesium. These metals do not react either with cold or hot water.
   2Al + 3H2O  ➡    Al2O3 + 3H2


3. Reaction of Metals with Dilute Acids:

  Reactive metals displace hydrogen gas from acids such as dilute hydrochloric acid or dilute sulphuric acid.

4. Reaction of Metals with chlorine:  

Metals react with chlorine to form metal chlorides. Not all the metals react with chlorine at room temperature.

5. Reaction of Metals with Hydrogen:  

metals do not react with hydrogen. Only highly reactive metals such as sodium, potassium, calcium & magnesium react with hydrogen to form compounds known as metal hydrides.

6. Reaction with other Metal salts.

7. Reducing Behaviour:  

Metals can lose electrons, thus they act as reducing agents. 
    2Na   Cl2    ➡    2NaCl

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