Non metals, electronegative character and comparison of reactivity of the halogens

Elements that conduct heat and electricity very poorly are called non-metals.

Non metals are generally gases, brittle solids at room temperature except bromine is is liquid. There are several elements that have mixed properties of metals and non metals. These elements are known as metalloid.

Electronegative character or non metallic character

It is reverse of electropositive character. It is the tendency of an element to gain the electron.

X + e- ---------------> X-

Where X stands for any non-metal.

Non- metals have small atomic size, higher nuclear charge and hence, high electronegativity. Electronegativity decreases down the group. Hence e electronegative character also decreases.

Trends in periodic table

Along the period

As we move from left to right in a period, electronegativity increases due to increase in nuclear charge and decrease in atomic size. Hence, electronegative character or non metallic character also increases.

Question: in each of the following pairs of elements, identify which element is more non-metallic?

a. N or O

b. F or Cl

Solution

O is more non metallic because of greater nuclear charge and small atomic size as compared to N which has relatively lower nuclear charge and greater atomic size.

F is more non metallic because of lesser sheilding effect and small atomic size as compared to Cl which has relatively greater sheilding effect and greater atomic size.

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