http://www.ck12.org Chapter 8. Ionic and Metallic Bonding
N+ 3 e− → N^3 −
1 s^22 s^22 p^31 s^22 s^22 p^6 (octet)All of these anions are isoelectronic with each other and with neon. They are also isoelectronic with the three
cations from the previous section. Under typical conditions, a maximum of three electrons will be gained during the
formation of anions.
Outer electron configurations are constant within a group, so this pattern of ion formation repeats itself for Periods
3, 4, and so on (Figure8.1).
FIGURE 8.1
It is important not to misinterpret the concept of being isoelectronic. A sodium ion is very different from a neon
atom (Figure8.2) because their nuclei contain different numbers of protons. One is an essential ion that is a part of
table salt, while the other is an unreactive gas that makes up a very small part of the atmosphere. Likewise, sodium
ions are very different than magnesium ions, fluoride ions, and all the other members of this isoelectronic series
(N^3 −, O^2 −, F−, Ne, Na+, Mg^2 +, Al^3 +).
You can go to http://web.jjay.cuny.edu/~acarpi/NSC/3-atoms.htm to see animations of atoms and ions.
Learning the octet rule can be fun! Watch this music video about the octet rule: http://www.youtube.com/watch
?v=WzWk-mx_14E (6:30)