Question

(a) What are valence electrons? (b) How many valence electrons does a nitrogen atom possess? (c) An atom has the electron configuration \(1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{2} .\) How many valence electrons does the atom have?

Short answer

(a) Valence electrons are the outermost electrons in an atom that participate in chemical bonding, usually in the highest energy level. (b) A nitrogen atom has 5 valence electrons. (c) The atom with electron configuration \(1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{2}\) has 4 valence electrons.

Step-by-step solution

Definition of Valence Electrons

Valence electrons are the outermost electrons in an atom that participate in chemical bonding. They are usually the electrons in the highest energy level (highest principal quantum number) of an atom.

Valence Electrons in a Nitrogen Atom

A nitrogen atom has an atomic number of 7. Therefore, its electron configuration follows the order 1s², 2s², 2p³. The electrons in the highest energy level (n = 2) are 2s² and 2p³. So, a nitrogen atom has 5 valence electrons.

Valence Electrons in the Given Atom

The given electron configuration is 1s² 2s² 2p⁶ 3s² 3p². The highest energy level (principal quantum number) is n = 3. In this energy level, there are 3s² and 3p² electrons. So, the atom has 2 + 2 = 4 valence electrons.