PHYSICAL AND CHEMICAL PROPERTIES OF METALS CLASS 8,10
Physical Properties of Metals:
1) Metals are good conductor of heat and electricity.
2) Metals are ductile. (It means that they can be converted into thin wires)
3) They are malleable. (It means that they can be converted into thin sheets)
4) They are lustrous(shiny).
5) They are sonorous(make sound).
6) Metals have high density.
7) All metals are in the form of solid, except mercury.
8) Metals are very hard, except sodium(Na) and Potassium(K).The hardest metal is Titanium.
9) The melting and boiling point of metals is very high, except gallium.
Physical Properties of Non-metals:
1) Non-metals are bad conductor of heat and electricity, except graphite.
2) Non-metals are non-ductile. (It means that they cannot be converted into thin wires)
3) They are non-malleable. (It means that they cannot be converted into thin sheets)
4) They are non-lustrous(not shiny), except diamond and iodine.
5) They are non-sonorous(doesn't make sound).
6) Non-metals have less density.
7) All Non-metals are in the form of solid, liquid and gas.
8) Non-metals are brittle, except diamond.
9) The melting and boiling point of Non-metals is less.
Chemical Properties of Metals:
What happens when Metals are burnt in Air?
When metals are burnt in air they combine with oxygen(O₂) to form metal oxide.
Metal + Oxygen → MetalOxide
Example:(1) Copper + oxygen (heat)→ CopperOxide
2Cu + O₂ → 2CuO
(2) Aluminium + oxygen (heat) → AluminiumOxide
4Al + 3O₂ → 2Al₂O₃
What happens when Metals react with Water?
Metals reacts with water to produce metal oxide along with hydrogen gas.
Metal + Water → MetalOxide +Hydrogen
If the metal oxide formed is soluble in water it further form metal hydroxide.
MetalOxide + Hydrogen → MetalHydroxide
Some metals react with water vigorously. That reaction is highly exothermic. The hydrogen evolved in that reaction catches fire immediately.
Example:(1) Potassium + Water → PotassiumHydroxide + Hydrogen + heat
2K + 2H₂O → 2KOH + H₂ + heat
(2) Sodium + Water → SodiumHydroxide + Hydrogen + heat
2Na + 2H₂O → 2NaOH + H₂ + heat
While some metals does not react with water vigorously. Thus they are not exothermic.
Example:(1) Calcium + Water → CalciumHydroxide + Hydrogen
Ca + 2H₂O → Ca(OH)₂ + H₂
Also some metals like lead, gold, silver and copper do not react with water. Hence it is not necessary that every metal reacts with water.
What happens when Metals react with Acids?
In Chapter 2 we already learnt that metals react with acid to produce salt and water.
Metal + Acid → Salt + Hydrogen
Example:(1) Zinc + Hydrochloric acid → ZincChloride + Hydrogen
Zn + 2HCL → ZnCl₂ + H₂
What happens when Metals react with Solutions of other Metals Salts?
When metal reacts with Solutions of other metals salts the high reactive metal displaces the less reactive metal from its compound.
Metal X + Salt solution of Metal B → Salt solution of Metal A + Metal B
We learned about displacement reaction in chapter 2.
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