Practice Valence Electron in Chemistry

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

An electron residing in the outermost (highest-energy) occupied shell of an atom, available for participation in chemical bonding through sharing, gaining, or losing. The number of valence electrons determines an element's bonding behavior and chemical reactivity.

The electrons that 'reach out' to other atoms. These do the bonding.

Example 1

easy
How many valence electrons does nitrogen (Z = 7) have?

Example 2

medium
Explain why elements in Group 17 (halogens) are highly reactive, using the concept of valence electrons.

Example 3

easy
Determine the number of valence electrons for: (a) carbon, (b) sulfur, (c) argon.

Example 4

medium
Sodium has electron arrangement 2,8,1. How many valence electrons does it have, and is it more likely to lose one electron or gain seven?
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