Exercise 9.8
Nitrogen has five valence electrons. Draw the structure of the nitrogen molecule ().
Not cross-checked
NCERT prints no numerical answer for this exercise, so this working has not been cross-checked against the book.
Two nitrogen atoms share three pairs of electrons, giving a triple bond: \(\displaystyle N \equiv N\).
Nitrogen has $\displaystyle 5$ valence electrons and needs $\displaystyle 3$ more for an octet; neither atom can take $\displaystyle 3$ from the other, so each contributes $\displaystyle 3$ electrons to be shared.
After sharing, each nitrogen counts \(\displaystyle 5 + 3 = 8\) valence electrons — a complete octet, so \(\displaystyle N_2\) is stable.
The drawing must contain:
two atoms labelled N, side by side, each starting with its $\displaystyle 5$ valence electrons marked round it;
dots for one atom's electrons and crosses for the other's, so the reader can see which electron came from where;
three shared pairs ($\displaystyle 6$ electrons) drawn in the overlap between the two symbols;
one lone pair left on each nitrogen, drawn on its outer side;
the line formula N≡N written alongside, the three lines standing for the three shared pairs.