THE PERIODIC TABLE

4.10 - Melting Point and Boiling Point Trends

The melting point and boiling point are measures of the attractive forces between atoms or molecules. Elements, such as metals, that have strong attractive forces have higher melting points and boiling points than nonmetals, which have very weak forces of attraction.

(i)The Halogens

The physical states of the halogens at room temperature varies from gas to liquid to solid as one moves down the group. As a result, the melting points and boiling points increase as one moves down the group.

(ii)The Alkali Metals

The alkali metals show a decrease in melting points and boiling points due to the weaker metallic bonds between atoms as their size increase down the group.

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