Question

State the trends in physical properties on moving down the group. Give an example to illustrate.

Answer 1

The melting and boiling points of metals decrease on going down the group. Example: Observe the trend in group 1 elements given in the following table:

Metals	m.p	b.p
Li	180.5°C	1347°C
Na	94.5°C	883°C
K	63.5°C	774°C

From the above table, it is clear that m.p. and b.p. decrease from Li to K.
The melting and boiling points of non-metals increase on going down the group.
Example: Observe the trend in Group 17 elements given in the following table:

Non-metals	m.p.	b.p.	Physical state
Fluorine	-219.6°C	-187°C	Gas
Chlorine	-101°C	-34.6°C	Gas
Bromine	-7.2°C	+58.8°C	Liquid
Iodine	+113.6°C	+183°C	Solid

From the above table, it is clear that m.p. and b.p. increase from F to I.