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Inorganic Pharmaceutical Chemistry 3

الكلية كلية العلوم للبنات     القسم قسم الكيمياء     المرحلة 3
أستاذ المادة محمد حامد سعيد الدهيمي       21/12/2012 19:05:41
Inorganic Pharmaceutical Chemistry
Lecture No. 3 Date :18/10 /2012
Dr. Mohammed Hamed
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Properties of Monatomic Ions
The electrons in the outermost shell (the ones with the highest value of n) are the most energetic, and are the ones which are exposed to other atoms. This shell is known as the valence shell. The inner, core electrons (inner shell) do not usually play a role in chemical bonding.
Elements with similar properties generally have similar outer shell configurations. For instance, we already know that the alkali metals (Group I) always form ions with a +1 charge; the "extra" s1 electron is the one that s lost:

IA Li 1s22s1 Li+ 1s2
Na 1s22s22p63s1 Na+ 1s22s22p6
K 1s22s22p63s23p64s1 K+ 1s22s22p63s23p6

The next shell down is now the outermost shell, which is now full — meaning there is very little tendency to gain or lose more electrons. The ion s electron configuration is the same as the nearest noble gas — the ion is said to be isoelectronic with the nearest noble gas. Atoms "prefer" to have a filled outermost shell because this is more electronically stable.
The Group IIA and IIIA metals also tend to lose all of their valence electrons to form cations.
IIA Be 1s22s2 Be2+ 1s2
Mg 1s22s22p63s2 Mg2+ 1s22s22p6
IIIA Al 1s22s22p63s23p1 Al3+ 1s22s22p6

• The Group IV and V metals can lose either the electrons from the p subshell, or from both the s and p subshells, thus attaining a pseudo-noble gas configuration.

IVA Sn [Kr]4d105s25p2 Sn2+ [Kr]4d105s2
Sn4+ [Kr]4d10
Pb [Xe]4f145d106s26p2 Pb2+ [Xe]4f145d106s2
Pb4+ [Xe]4f145d10
VA Bi [Xe]4f145d106s26p3 Bi3+ [Xe]4f145d106s2
Bi5+ [Xe]4f145d10
• The Group IV - VII non-metals gain electrons until their valence shells are full (8 electrons).

IVA C 1s22s22p2 C4- 1s22s22p6
VA N 1s22s22p3 N3- 1s22s22p6
VIA O 1s22s22p4 O2- 1s22s22p6
VIIA F 1s22s22p5 F- 1s22s22p6
• The Group VIII noble gases already possess a full outer shell, so they have no tendency to form ions.

VIIIA Ne 1s22s22p6
Ar 1s22s22p63s23p6
• Transition metals (B-group) usually form +2 charges from losing the valence s electrons, but can also lose electrons from the highest d level to form other charges.
B-group Fe 1s22s22p63s23p63d64s2 Fe2+ 1s22s22p63s23p63d6
Fe3+ 1s22s22p63s23p63d5
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