Chapter 5, Problem 1E

What is electronegativity? What are the periodic trends in electronegativity?

Interpretation Introduction

To determine: Definition of electronegativity and periodic trends in electronegativity.

Answer to Problem 1E

Solution:

Electronegativity is the tendency of an element to attract electrons.

In the periodic table, electronegativity increases along a period and decreases down a group.

Explanation of Solution

Electronegativity is a chemical property of some elements (like oxygen, nitrogen etc.), due to which an atom has the tendency to attract shared pair of electrons towards itself. This results in unequal distribution of electrons.

In the modern periodic table, elements are arranged in order of their increasing atomic number. For this reason, along a period, more and more electrons are added from left to right. As a result, the distance between the nucleus and valence electrons decreases. This increases the electronegativity.

However, down the groups, more and more electronic shells are added due to increase in atomic numbers. As a result, the distance between the nucleus and valence electrons increases. For this reason, electronegativity decreases down the group.

Example:

Electronegativity of oxygen is less than fluorine although both are Period 2 elements.

Electronegativity gradually decreases down group VII because the electronegativity of chlorine is less than fluorine although both elements belong to group VII.

Conclusion

Conclusion:

The electronegativity increases along a period and decreases down a group.