Chemical properties of metals

• There are generally 1, 2 or 3 electrons in the outermost shell of metals. The molecules of metals in vapour state generally have one atom. The lesser the number of valence electrons the more is the activity of the metal.
• Metals form cations by losing electrons.
• They generally form basic oxides.
• They are known as reducing agents because they ionize by losing electrons.

REACTION OF METALS

REACTION OF METALS WITH OXYGEN (OF AIR)

• When metals are burnt in air,  Metals react with oxygen to form metal oxides.

• Example: Sodium metal reacts with the oxygen of air at room temperature to form a basic oxide called sodium oxide:

• Some of the metal oxides dissolve in water to form alkalis.
• For example, Sodium oxide, a basic oxide reacts with water to form an alkali called sodium hydroxide:

• Potassium oxide, a basic oxide reacts with water to form an alkali called potassium hydroxide:

• In case of Magnesium, it does not react with oxygen at room temperature. But on heating, magnesium burns in air giving intense heat and light to form a basic oxide called magnesium oxide which is a  white powder:

• Magnesium oxide dissolves in water partially to form magnesium hydroxide solution:

• Aluminium metal burns in air, on heating, to form aluminium oxide:

• Aluminium oxide and zinc oxide shows both acidic and basic behavior. Hence they are amphoteric.
  • Aluminium oxide reacts with hydrochloric acid to form aluminium chloride (salt) and water:

• Aluminium oxide reacts with sodium hydroxide to form sodium aluminate (salt) and water:

• Iron metal does not burn in the air even on strong heating. Iron on reaction with  oxygen forms iron (II, III) oxide:

REACTION OF METALS WITH WATER

• When a metal reacts with water (cold water or hot water), then the products formed are metal hydroxide and hydrogen gas:

• Potassium reacts vigorously with cold water to form potassium hydroxide and hydrogen gas:

• Sodium reacts vigorously with water to form sodium hydroxide and hydrogen gas:

• Calcium reacts with cold water to form calcium hydroxide and hydrogen gas:

• Magnesium metal does not react with cold water. It  reacts with hot water to form magnesium hydroxide and hydrogen:

• Aluminium reacts with steam forming aluminium oxide and hydrogen gas:

REACTION OF METALS WITH DILUTE ACIDS

• When a metal reacts with a dilute acid, then a metal salt and hydrogen gas are formed:

• Sodium metal reacts violently with dilute hydrochloric acid forming sodium chloride and hydrogen:

• Magnesium reacts quite rapidly with dilute hydrochloric acid to form magnesium chloride and hydrogen gas:

REACTION OF METALS WITH SALT SOLUTIONS

• When a more reactive metal is put in the salt solution of a less reactive metal, then the more reactive metal displaces the less reactive metal from it salt solution.

• The Reaction of Zinc with Copper Sulphate Solution. Copper sulphate is a blue coloured solution. When a strip of zinc metal is dipped in the copper sulphate solution, the blue colour fades gradually due to the formation of colourless zinc sulphate solution, and results in the deposition of red-brown copper metal on the zinc strip:

• However, if a strip of copper metal is placed in zinc sulphate solution, then no reaction occurs.
• Reaction of Iron with Copper, Sulphate Solution. When a strip of iron metal (or iron nail) is dipped in copper sulphate solution, then the blue colour of copper sulphate solution fades gradually and red-brown metal is formed:

copper II sulphate    Iron          Iron II sulphate  copper

(blue solution)           (grey)    (greenish solution) (red-brown)

• Reaction of Copper with Silver Nitrate Solution. When a strip of copper metal is ­kept immersed in silver nitrate solution for a period of time, the solution gradually becomes blue and a shining greyish-white deposit of silver metal is formed on the copper strip: