1. Ionic Compounds The Loss or Gain of Electrons

2. Stable Atoms We know that atoms that are stable have either: A filled outer energy level – eight electrons (the octet rule). A filled outer energy level – eight electrons (the octet rule). Elements will lose or gain electrons to achieve this state. Elements will lose or gain electrons to achieve this state. Use the periodic table to see how many electrons the atom needs to be stable. Use the periodic table to see how many electrons the atom needs to be stable. Ex. O has 6, but wants 8. It adds 2e’s; It makes the ion O -2

3. Ions Ionic compounds start with ions Ionic compounds start with ions When naming an anion we will take the beginning of the name and add –ide. When naming an anion we will take the beginning of the name and add –ide. Ex. Cl- is called chloride, not chlorine When naming a cation we just use the name of the element plus the word ion. When naming a cation we just use the name of the element plus the word ion. Ex. Na+ is called sodium ion

4. Ionic Compounds Ionic compounds are called salts. Ionic compounds are called salts. Consist of a metal and a nonmetal. Consist of a metal and a nonmetal. A cation and an anion. There can be multiples of each. A cation and an anion. There can be multiples of each. It is the electrostatic attraction (opposites attract) between the positive cation and the negative anion that holds the compound in the solid state. It is the electrostatic attraction (opposites attract) between the positive cation and the negative anion that holds the compound in the solid state.

5. Characteristics of Ionic Compounds Strong bonds. Strong bonds. Solids. Solids. High melting points. High melting points. Exist as crystals with repeating units Exist as crystals with repeating units Can be soluble (dissolve in water) or insoluable Can be soluble (dissolve in water) or insoluable

6. Naming Ionic Compounds Always name the cation first. Always name the cation first. Change the suffix of the anion to –ide. Change the suffix of the anion to –ide. If the cation is a transition element the name MUST contain a Roman numeral. This represents its charge or oxidation state. If the cation is a transition element the name MUST contain a Roman numeral. This represents its charge or oxidation state. Example: KI – potassium iodide SrCl 2 – strontium chloride FeF 3 – iron(III) fluoride.

7. Polyatomic Ions Polyatomic ions are ions that consist of more than one element. Polyatomic ions are ions that consist of more than one element. It is very important to keep in mind that the charge on the polyatomic ion belongs to the entire molecule, not to just one atom within the molecule. It is very important to keep in mind that the charge on the polyatomic ion belongs to the entire molecule, not to just one atom within the molecule. NO 3 - nitrate polyatomic ion. SO 4 -2 sulfate polyatomic ion.

8. Polyatomic Ions You are responsible for memorizing the following polyatomic ions with respect to their formulas, names, and charges: (They are found on your ion chart) CH 3 COO -1 (C 2 H 3 O 2 -1 )acetate NH 4 +1 ammonium CO 3 -2 carbonate CrO 4 -2 chromate OH -1 hydroxide NO 3 -1 nitrate NO 2 -1 nitrite PO 4 -3 phosphate SO 4 -2 sulfate SO 3 -2 sulfite

9. Polyatomic Ions Ionic compounds containing polyatomic ions are named by: Ionic compounds containing polyatomic ions are named by: Naming the cation. Naming the cation. Naming the polyatomic ion. Naming the polyatomic ion. NaNO 3 – sodium nitrate Mg(OH) 2 – magnesium hydroxide

10. Writing Formulas Two methods to writing formula First method- add up charges; First method- add up charges; Write the cation first. Write the cation first. Write the anion last. Write the anion last. First method- The sum of the oxidation numbers or charges must equal zero. Ex. Calcium chloride First method- The sum of the oxidation numbers or charges must equal zero. Ex. Calcium chloride Ca +2 2xCl - = -2 CaCl 2 Second method – criss-cross Second method – criss-cross Ca +2 Cl -1 = CaCl 2 Ca +2 Cl -1 = CaCl 2

11. Writing and Naming Ionic Formulas Name the following ionic compounds: SrO Al(CH 3 COO) 3 CuSO 4 Name the following ionic compounds: SrO Al(CH 3 COO) 3 CuSO 4 strontium oxidealuminum acetate copper(II) sulfate strontium oxidealuminum acetate copper(II) sulfate KNO 3 CrPO 4 BaI 2 potassium nitratechromium(III) phosphate barium iodide