Regents Chemistry

1
Regents Chemistry

• Agenda
• Review electronegativity worksheet
• Ions and polyatomic Ions
• Calculating charges worksheet
• HW Finish worksheet

2
Charges on ionsreview

• 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
  waysbut can we have more?

4
Polyatomic Ions

• 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)-
2-
5
5-6 -1
1 x 5 5
3 x 2- -6
6
Practice Problem
S6O2-42- 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 -3 - 2 -1
CN-
7
Why is this important?

• Polyatomic ions combine just like other ions to
  form ionic substances
• K NO3- ? KNO3
• Cu2 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