form ions from elements

Formation
of Ions
from

Elements

Example 1: sodium

Na

1 22 22 63 1

The valence electron
configuration for
sodium shows a
single valence
electron (highlighted
in red).

Na → Na+ + −

−
1 22 22 63 1

Sodium tends to form an
ion by losing its one valence
electron. The loss of one
electron results in a sodium
cation with a +1 charge.

This loss of the previous
valence electron allows
sodium to expose a full
valence shell underneath.
Because this is the electron
configuration of neon, this is
a more stable configuration.
The sodium ion is much more
stable (and less reactive)
than the sodium atom.

Na+ 1 22 22 6 Ne



Example 2: fluorine, a nonmetal

F

1 22 22 5

Fluorine has a
valence electron
configuration with 7
valence electrons
(highlighted in red).

F + − → F−

−
1 22 22 5 6

Fluorine makes a
fluoride ion by
gaining one electron.
This electron is
added to its valence
shell.

The fluoride ion then has
the same electron
configuration as neon
and is therefore more
stable than the fluorine
atom.

F− 1 22 22 6 Ne