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Regents Chemistry. Agenda Review electronegativity worksheet Ions and polyatomic Ions Calculating charges worksheet HW: Finish worksheet. Charges on ions…review. Cations – are positive ions that form as a result of a loss of electrons Ex: Cu 2+ , K +
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Regents Chemistry • Agenda • Review electronegativity worksheet • Ions and polyatomic Ions • Calculating charges worksheet • HW: Finish worksheet
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-
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?
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-
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
Practice Problem S6+O2-42- 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-
Why is this important? • Polyatomic ions combine just like other ions to form ionic substances K+ + NO3- KNO3 Cu2+ + NO3- ? Cu(NO3)2 Worksheet
Practice • Name the following: • CaSO4 • Na2C2O4 • Al(NO3)3 • Au2(SO3)3 Calcium Sulfate Sodium Oxalate Aluminum Nitrate Gold (III) Sulfite
Practice • Write chemical formulas for the following: • Lithium Carbonate • Potassium cyanide • Tin (IV) permanganate • Copper (II) dichromate Li2CO3 KCN Sn(MnO4)4 CuCr2O7