1. CHAPTER 3 Ionic Compounds General, Organic, & Biological Chemistry Janice Gorzynski Smith

2. CHAPTER 3: Ionic Compounds 2 Smith. General Organic & Biolocial Chemistry 2nd Ed. Learning Objectives:  Octet Rule & Predicting ionic Charges  Ionic Bonds  Formation of cations by metals  Formation of anions by nonmetals  Metals capable of forming multiple charges  Formation of electronically neutral ionic compounds  Polyatomic ions  Naming Ionic Compounds  Properties of Ionic Compounds  High Melting & Boiling Points  Conductive aqueous solutions

3. 3 Bonding Definition Bonding is the joining of two atoms in a stable arrangement. There are two different kinds of bonding: Elements will gain, lose, or share electrons to reach the electron configuration of the noble gas closest to them in the periodic table. 1.Ionic bonds result from the transfer of electrons from one element to another. 2.Covalent bonds result from the sharing of electrons between two atoms. Smith. General Organic & Biolocial Chemistry 2nd Ed.

4. 4 Bonding Definition Li F

5. 5 Bonding Ionic Bonds vs Covalent Bonds Ionic bonds form between: A metal (left side periodic table) A nonmetal (right side periodic table) Covalent bonds are formed when two nonmetals combine, or when a metalloid bonds to a nonmetal. Smith. General Organic & Biolocial Chemistry 2nd Ed.

6. 6 Ions Cations Cations are positively charged ions. A cation has fewer electrons (e − ) than protons. the sodium atomthe sodium ion Smith. General Organic & Biolocial Chemistry 2nd Ed.

7. 7 Ions Anions Smith. General Organic & Biolocial Chemistry 2nd Ed. Anions are negatively charged ions. An anion has more e − than protons. the chlorine atomthe chlorine ion

8. 8 Ions The Octet Rule Smith. General Organic & Biolocial Chemistry 2nd Ed. The octet rule: a main group element is especially stable when it possesses an octet of e − in its outer shell. octet = 8 valence e −

9. 9 Ions Charge as Determined by Periodic Group Smith. General Organic & Biolocial Chemistry 2nd Ed. group 1A: group 2A: group 3A: M 1 valence e − M + + e − M 2 valence e − M 2+ + 2e − M 3 valence e − M 3+ + 3e − the cation charge = the group number

10. 10 Ions Charge as Determined by Periodic Group Smith. General Organic & Biolocial Chemistry 2nd Ed. group 6A:X 6 valence e − + 2e − X 2− group 7A:X 7 valence e − + e − X − the anion charge = 8 – group number charge = 8 – 6 = 2 charge = 8 – 7 = 1

11. 11 Ions Main Group Ions Smith. General Organic & Biolocial Chemistry 2nd Ed.

12. 12 Ions Metals with Variable Charges Smith. General Organic & Biolocial Chemistry 2nd Ed.

13. 13 Ions Biologically Relevant Ions Smith. General Organic & Biolocial Chemistry 2nd Ed. http://www.drcruzan.com/Chemistry_PeriodicTable.html

14. 14 Ionic Compounds Definition & Solid Structure Smith. General Organic & Biolocial Chemistry 2nd Ed. The sum of the charges in an ionic compound must be zero overall. Ions will arrange to maximize anion-cation attractions and minimize anion-anion and cation-cation repulsions

15. 15 Ionic Compounds Charge Balance Smith. General Organic & Biolocial Chemistry 2nd Ed.

16. 16 Ionic Compounds Formula for Ionic Compounds Smith. General Organic & Biolocial Chemistry 2nd Ed. HOW TO Write a Formula for an Ionic Compound Step [1] Identify which element is the cation and which is the anion. Step [2] Determine how many of each ion type is needed for an overall charge of zero.  When the cation and anion have different charges, use the ion charges to determine the number of ions of each needed. Step [3] To write the formula, place the cation first and then the anion, and omit charges.

17. 17 Ionic Compounds Criss-Cross Rule Smith. General Organic & Biolocial Chemistry 2nd Ed. “Criss-cross” rule  Make magnitude of charge on one ion into subscript for other  When doing this, make sure that subscripts are reduced to lowest whole number. Al 2 O 3 Al 3+ O 2–

18. 18 Naming Main Group Cations Smith. General Organic & Biolocial Chemistry 2nd Ed. Main group cations are named for the element from which they are formed. Na + K+K+ Ca 2+ Mg 2+ sodiumpotassium calcium magnesium

19. 19 Naming Multiple Charge Cations Smith. General Organic & Biolocial Chemistry 2nd Ed. Systematic name: Follow the name of the cation by a Roman numeral in parentheses to indicate its charge. Fe 2+ iron(II) Fe 3+ iron(III) Common name: Use suffix “-ous” for the cation with a smaller charge and suffix “-ic” for the cation with a higher charge. ferrous ferric Fe 2+ Fe 3+

20. 20 Naming Anions Smith. General Organic & Biolocial Chemistry 2nd Ed. Anions are named by replacing the ending of the element name by the suffix “-ide.”

21. 21 Naming Ionic Compounds Smith. General Organic & Biolocial Chemistry 2nd Ed. Name the cation and then the anion. Do not specify the charge on the ion. Do not specify how many ions of each type are needed to balance charge. Na + sodium F − fluoride NaF sodium fluoride + Mg 2+ magnesium Cl − chloride MgCl 2 magnesium chloride +

22. 22 Naming Ionic Compounds Smith. General Organic & Biolocial Chemistry 2nd Ed. HOW TO Name an Ionic Compound Step [1] Determine the charge on the cation. Step [2] Name the cation and the anion  If the cation could be multiple charges indicate the charge with roman numerals or with a –ous / -ic suffix. Step [3] Write the name of the cation first then the name of the anion

23. 23 Smith. General Organic & Biolocial Chemistry 2nd Ed. HOW TO Derive the Formula from the Name of an Ionic Compound Step [1] Identify the cation and the anion. Step [2] Determine the charge on the cation and anion. Step [3] Balance the charges. Step [4] Write the formula with the cation first and use subscripts to communicate charge balance. Naming Ionic Compounds

24. Properties Physical Properties of Ionic Compounds Ionic compounds are crystalline solids with very high melting and boiling points. When ionic compounds dissolve in water, they separate into cations and anions, increasing the conductivity of the solution. NaCl +  water solution

25. 25 Polyatomic Ions Definition Smith. General Organic & Biolocial Chemistry 2nd Ed. A polyatomic ion is a cation or anion that contains more than one atom. The multiple atoms are held together with covalent bonds The molecule has an overall charge associated with it.

26. 26 Polyatomic Ions Writing Formula Smith. General Organic & Biolocial Chemistry 2nd Ed. When a cation and anion of equal charge combine, only one of each ion is needed. Na + NO 2 − +NaNO 2 zero overall charge Ba 2+ SO 4 2− +BaSO 4 zero overall charge

27. 27 Polyatomic Ions Writing Formula Smith. General Organic & Biolocial Chemistry 2nd Ed. When a cation and anion of unequal charge combine, use the ionic charges to determine the relative number of each ion that is needed. Mg 2+ OH − +Mg(OH) 2 zero overall charge +2 charge means 2 OH − anions are needed. −1 charge means 1 Mg 2+ anion is needed.

28. 28 Polyatomic Ions Naming Ionic Compounds Smith. General Organic & Biolocial Chemistry 2nd Ed. Name the cation and then the anion. Do not specify the charge on the ions. Do not specify how many ions of each type are needed to balance charge. Use –ite suffix if 1 or less Oxygen atoms in anion Use –ate suffix if more Oxygen atoms in anion Use bi- prefix or write hydrogen if H part of anion The same rules are followed for naming standard ionic compounds: NaHCO 3 Al 2 (SO 4 ) 3 sodium bicarbonatealuminum sulfate