Answer
Please see the work below.
Work Step by Step
The elements of the second period from group 1A to group 7A are Li, Be, B, C, N, O, F respectively.
Their electronic configurations are,
Li - $1s^{2}2s^{1}$
Lithium contains one electron in its valence shell.
Be - $1s^{2}2s^{2}$
Beryllium contains two electrons in its valence shell.
B - $1s^{2}2s^{2}2p^{1}$
Boron contains three electrons in its valence shell.
C - $1s^{2}2s^{2}2p^{2}$
The carbon contains four electrons in its valence shell.
N - $1s^{2}2s^{2}2p^{3}$
Nitrogen contains five electrons in its valence shell.
O - $1s^{2}2s^{2}2p^{4}$
Oxygen contains six electrons in its valence shell.
F - $1s^{2}2s^{2}2p^{5}$
Fluorine contains seven electrons in its valence shell.
The valence shell electrons are represented as dots in Lewis symbols.
