1. Regents Chemistry Agenda Review electronegativity worksheet
Ions and polyatomic Ions
Calculating charges worksheet
HW: Finish worksheet

2. Charges on ions…review
Cations – are positive ions that form as a result of a loss of electrons
Ex: Cu2+, K+
Anions – are negative ions that form as a result of a gain of electrons
Ex: O2-, F-

3. Bonds
Ionic substances result from the donation of one or more electrons by a metal and acceptance of the electrons by a nonmetal
Covalent bonds result from the sharing of electrons
We have seen two atoms bonded in both of these ways…but can we have more?

4. Polyatomic Ions NO3- SO42-
Polyatomic ions are elements that are covalently bonded together but contain an overall net charge and the ability to act like an ionic compound.
Example
NO3-
SO42-

5. Calculating Overall Net Charge
We are given the overall net charge on
specific polyatomic ions on our
reference tables..however, we need to
understand how to calculate
these ourselves
NO3-
(NO3)-
Can be viewed as
Assigned oxidation
Values from table
(N O3)- 5+ 2-
5-6 = -1
1 x 5+ = +5
3 x 2- = -6

6. Practice Problem S6+O2-42- SO42- CN- 1 x +6 = +6 4 x –2 = -8
-8 +6 = -2
SO42-
If both atoms have
multiple states, the
atom with the higher
electronegativity gets
the negative charge
1N x -3 = -3
1C x +2 = +2
= -1
CN-

7. Why is this important? K+ + NO3-  KNO3 Cu2+ + NO3-  ? Cu(NO3)2
Polyatomic ions combine just like other ions to form ionic substances
K NO3-  KNO3
Cu NO3-  ?
Cu(NO3)2
Worksheet

8. Practice Name the following: CaSO4 Na2C2O4 Al(NO3)3 Au2(SO3)3
Calcium Sulfate
Sodium Oxalate
Aluminum Nitrate
Gold (III) Sulfite

9. Practice Write chemical formulas for the following: Lithium Carbonate
Potassium cyanide
Tin (IV) permanganate
Copper (II) dichromate
Li2CO3
KCN
Sn(MnO4)4
CuCr2O7