Unit #1Unit #2Unit #3Unit #4Unit #5Unit #6Unit #7Unit #8Unit #9Unit #10
spacerUNIT # 4  
spacerspacerIntroduction
spacerspacerObjectives
spacerspacerReading


spacer4.1 The Periods
spacer4.2 The Groups
spacerGroup IA - Alkali metals
spacerGroup IIA - Alkaline earth metals
spacerGroup VIIA - Halogens
spacerGroup VIIIA - Noble gases
spacer4.3 Metals,
spacerNonmetals,
spacerSemimetals

spacerProperties of Metals
spacerProperties of Nommetals
spacerProperties of Semimetals
spacerSummary
spacer4.4 Metallic
spacerBonding

spacer4.5 Octet
spacerRule

spacer4.6 Ions
spacer
4.7 Covalent
spacerBonding

spacerCovalent Bonding & Groups
spacer
4.8 Atomic
spacerSize

spacer
4.9 Ionic
spacerSize

spacerIonic Size of Metal Ions
spacerIonic Size of Nonmetal Ions
spacerIonic Size for Isoelectronic Series
spacer
4.10 mp/bp
spacerTrends
spacer
4.11 Metallic
spacerTrend


spacer** More
spacerspacerperiodic
spacerTrends
**


spacerspacerProblems
spacer1 | 2 | 3
spacerspacerCrossword
spacerspacerHow well do you
spacerknow your
spacerPeriodic Table?
Unit #4THE PERIODIC TABLE

4.9 - Ionic Size

4.9.3 - Ionic Size for Isoelectronic Series

Isoelectronic ions are ions that have the same number of electrons. There are many ions that are isoelectronic.

For example:

Isoelectronic ions number of electrons
1. Na+, F- 10 electrons
2. S2-, Cl-, K+, Ca+2 18 electrons

Let's look at the first example of isoelctronic ions, Na+, F- (ions both have 10 electrons):

  • Na+ has 11 protons, a nuclear charge of +11.
  • F- has 9 protons, a nuclear charge of +9.

We expect the Na+, with its greater nuclear charge will have a greater attraction of its electrons than F-.

Na+ has a smaller ionic radius than F-

Let's look at the second example of isoelctronic ions, S2-, Cl-, K+, Ca+2 (ions all have 18 electrons):

  • S2- has 16 protons, a nuclear charge of +16.
  • Cl- has 17 protons, a nuclear charge of +17.
  • K+ has 19 protons, a nuclear charge of +19.
  • Ca+2 has 20 protons, a nuclear charge of +20.

We expect the Ca+2, with the greatest nuclear charge will have a greatest attraction of its electrons. S2- has the smallest nuclear charge will not have as much pull of its electrons toward the nucleus. Therefore, the ionic size:

Ca+2 < K+ < Cl- < S2-
(smallest)                    (largest)

 

For isoelectronic ions, the radius decreases as the positive nuclear charge increases.

 

Back


All contents copyrighted © 1996-2006
British Columbia Institute of Technology
Chemistry Department - 3700 Willingdon Avenue
Burnaby, B.C. Canada V5G 3H2