Name___________________
1/5/2012
Electron Configuration of Ions
1) Group the following elements into cation forming and anion forming elements.
Fluorine, Sodium, Nickel, Cobalt, Oxygen, Sulfur, Magnesium
Cation forming
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Anion forming
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2) Next to each element above, write how many electrons that element gains or loses to form an
ion with a full octet.
3) What is the net charge on each of these atoms before they form ions? ____
4) What is the net charge on ions of each of the following elements?
a. Fluorine _______________
b. Sodium _______________
c. Nickel _______________
d. Cobalt _______________
e. Oxygen _______________
f. Sulfur _______________
g. Magnesium _______________
Chemical Symbols for Ions
We can represent an ion symbolically with its element’s chemical symbol and its net charge
For example, potassium is in group 1, so it has 1 valence electron.
Potassium loses 1 valence electron to acquire a full octet.
This leaves potassium with a +1 charge
K  e- + K +
K+ is how we write a potassium ion.
If potassium lost two electrons, how would you write the ion? _____
If potassium gained an electron, how would you write the ion? _____
5) Represent each of the following ions symbolically
a. Fluoride _______________
b. Sodium _______________
c. Nickel _______________
d. Cobalt _______________
e. Oxide _______________
f. Sulfide _______________
g. Magnesium _______________
Ionization Reactions
You saw an example of an ionization reaction above.
Potassium gives off an electron to form a potassium ion (K+)
K  e- + K+
Non-metals gain electrons to form anions
Cl + e-  ClWrite ionization reactions for the following elements
a. Fluorine _______________
b. Sodium _______________
c. Nickel _______________
d. Cobalt _______________
e. Oxygen _______________
f.
Sulfur _______________
g. Magnesium _______________
Electron configurations of ions
We’ve practiced two methods of writing electron configurations for atoms
Sodium:
We can apply the same principles to write an electron configuration of ions.
Pay careful attention to how many electrons an ion has before writing its electron configuration.
Hint: Ions must have full valence shells (i.e. full outermost s and p orbitals)
Write the electron configurations in two ways for each of the following ions
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Fluorine
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Sodium
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Nickel
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Cobalt
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Oxygen
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Sulfur
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Magnesium
Reflection questions
1) From which orbitals do cobalt and nickel atoms lose electrons when they form ions?
2) Go through the seven electron configurations you drew. Next to each, write the element that
has the same electron configuration (i.e., when it’s atoms have an equal number of protons and
electrons). For which elements is this impossible?