Page 7 - 3. Lessson Notes- Ch-3 Chemical properties of Metal & Non metals -PDF

• Exceptions-
1. Metals such as potassium and sodium react so vigorously that they catch
fire if kept in the open.
Hence, to protect them from coming in contact with oxygen & moisture, they
are kept immersed in kerosene oil.

2. At ordinary temperature, the surfaces of metals such as magnesium,
aluminium, zinc, lead, etc., are covered with a thin layer of oxide. The
protective oxide layer prevents the metal from further oxidation.

3. Iron does not burn on heating but iron filings burn vigorously when
sprinkled in the flame of the burner.
Reason- Smaller the particle size, greater is the exposed surface area.
Hence, absorption of heat increases many fold, and they burn vigorously.

4. Copper does not burn, but the hot metal is coated with a black coloured
layer of copper(II) oxide on prolonged heating.

5. Silver and gold do not react with oxygen even at high temperatures.
Reason- Ag & Au are least reactive metals.

6. White/Yellow Phosphorus has a very low ignition temperature and
o
catches fire at about 30 C.
So, it’s stored under water as water is a non-supporter of combustion.
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