All About Ions
The Noble Gases (He  Rn) no not normally gain or lose electrons to other elements. This is because they
have a complete set of valence electrons, which is the most stable electron configuration.
All other elements have some tendency to gain or lose electrons in order to have complete set of valence
electrons (and thereby “look like” a Noble Gas). Since all Noble Gases other than Helium have 8 valence
electrons, this is called the Octet Rule.
Octet Rule: all elements tend to gain or lose electrons in order to have a complete set of eight valence
electrons (except for H, Li, and Be which mimic He with 2 valence electrons).
Metals and non-metals approach the octet rule in opposite ways.
Non-metals have a strong pull on electrons, so they gain electrons to get an octet.
Metals have loose electrons, so metals always lose electrons to get an octet.
Example:
Phosphorus is a non-metal, so it will gain the three extra electrons it needs to “look like” Argon.
Aluminum is a metal, so it will lose its valence electrons to “look like” Neon.
Example: Fluorine atoms have 7 valence electrons, so they tend to gain 1 more electron to have a full octet
and “look like” Neon. But in gaining an electron, the F atoms become F ions with a -1 charge,
since they now have one more electron (negative charge) than they have protons.
All elements in group 7 (F  At) tend to gain one electron, forming ions with a -1 charge. So…
Important! Do this or you are DOOMED!!!!
1) On the front side of your Periodic Table write “-1” in the space next to the symbol for each of the
following group 7 elements: F, Cl, Br, and I (omit At)
2) Since non-metals in group 6 tend to gain 2 electrons in order to have an octet, write “-2” in the space
next to the symbol for each of the following elements: O and S (the others don’t form negative ions)
3) Write “-3” in the space next to the symbol for each of the following elements: N, P, and As
4) Write “-4” in the space next to the symbol for each of the following elements: C and Si
Remember that metals lose electrons to get an octet, so they always form positive ions, since they end up
with more protons than electrons.
To determine the charge of a metal ion, look at the number(s) of its “Oxidation States” which can be found
on the right side of the box for each element. (see diagram on the back of this page)
Example:
Ca is a metal, so it loses its two valence electrons to “look like” Argon. This gives Ca ions a +2 charge. If
you look in the box for Ca on the periodic table you will see that its Oxidation State number is 2 indicating
the charge of the ion.
Sn is also a metal, so it loses electrons in order to “look like” Kr. It usually loses 4 electrons, forming a +4
ion, but sometimes it only loses 2. When you look at its Oxidation States, you will see 4 2, but since 4 is
shown in bold, we know that the most common ion formed by Sn is +4
Important!!!!
Using Oxidation State information to determine ionic charge only works for metals!
For non-metals, use the negative numbers that you wrote in the box for each non-metal element.
Naming ions:
Non-metal ions always end in the suffix “-ide”. So the difference between Chlorine and Chloride is that
Chlorine is an atom, and Chloride is an ion.
Here is the complete list of non-metal ions, in increasing order of atomic number:
Ion
Name
C-4
Carbide
N-3
Nitride
O-2
Oxide
-1
F
Fluoride
Si-4
Silicide
P-3
Phosphide
S-2
Sulfide
Cl-1
Chloride
As -3
Arsenide
Br-1
Bromide
-1
I
Iodide
For metal ions, the name doesn’t change, so Al+3 is still called Aluminum, and Na+1 is Sodium.
If the metal can form ions of more than one charge, then you indicate the charge by following the name of
the metal with a Roman numeral.
Example:
Since Nickel can form either +2 or +3 ions, we need a way to differentiate the two different ions, so
Ni+2 is called Nickel (II) and Ni+3 is called Nickel (III)
However, since Zn only forms Zn+2 ions, we just call it Zinc, not Zinc (II)
All About Ions
Name ___________________________
1. Read the notes “All About Ions” and do exactly as it says under the heading:
Important! Do this or you are DOOMED!!!!
Look at the Periodic Table at the front of the class if you need clarification.
2. Give the chemical symbol of the Noble Gas that each of the following would try to look like by gaining
or losing electrons. Example: F would try to look like Ne
Si _______
Hg _______
As_______
Mg _______
I_______
Ra _______
3. For each of the following, write either “gain” or “lose” to indicate whether the element gains or loses
electrons when forming an ion, then indicate the most likely number of electrons that are gained or lost.
If it does neither, write “none”.
Example: F = gain 1
N_____________
Au _____________
Si _____________
Ag _____________
Nb _____________
Ar _____________
Os _____________
U _____________
4. Give the most likely charge for the ions formed by each of the following elements:
Example: F = -1
Cr_____________
Sr_____________
S_____________
Pb_____________
C _____________
Fe_____________
Pa_____________
As _____________
5. Give the name of the ion most likely formed by each of the following elements
Example: F = Fluoride
Cr________________
Sr________________
S________________
Pb________________
C ________________
Fe________________
Pa________________
As ________________
When naming an ionic compound, you simply give the name of each ion. It’s as easy as that. Just
remember to capitalize each ion’s name, and include Roman numeral if the metal forms more than one ion.
Example:
What is the name of the compound formed by combining Al +3 and F-1 ions? Aluminum Fluoride
(Aluminum only forms +3 ions, so we don’t use Roman numerals)
What is the name of the compound formed by combining Ni +3 and F-1 ions? Nickel (III) Fluoride
(Nickel forms both +2 and +3 ions, so we have to specify with Roman numerals)
5. Name the compound formed by combining the following ions:
V+4 and P-3 _____________________________________________________
Cr+6 and I-1_____________________________________________________
Zr+4 and C-4_____________________________________________________
Cu+1 and S-2 _____________________________________________________
Al+3 and As-3 _____________________________________________________