1. Slide 1 Section 3.5 Ions and Their Compounds Objectives  To describe the formation of ions from their parent atoms  To learn to name ions  To predict which ion a given element forms by using the periodic table  To describe how ions combine to form neutral compounds

2. Slide 2 IONS Neutral atoms have the same number of protons and electrons – net charge is zero Neutral atoms have the same number of protons and electrons – net charge is zero Ions are charged atoms or groups of atoms Ions are charged atoms or groups of atoms Ions are formed when an atom loses or gains one or more electrons Ions are formed when an atom loses or gains one or more electrons Na 23 11 Consider Sodium-23 Protons?Neutrons? Electrons? What happens if sodium loses an electron? What is the charge? 1112 11 +1 11 protons, 10 electrons Sodium ion – Na +

3. Slide 3 Cations & Anions  Cation – An atom that loses electrons and has a positive charge  Elements in Group I, II, III  Transition Metals  Anion – An atom that gains electrons and has a negative charge  Elements in Groups VI, and VII

4. Slide 4 Ions and the Periodic Table

5. Slide 5 Ionic Compounds Ionic Compounds -- A compound that results when a metal reacts with a nonmetal to form cations and anions Ionic Compounds -- A compound that results when a metal reacts with a nonmetal to form cations and anions Ionic Compounds Ionic Compounds –Must be heated to a very high temperature to melt –Must be heated even hotter to boil –As solids, they do not conduct electricity –When melted, they are great conductors –When dissolved in water, solution conducts electricity

6. Slide 6 Formula for Ionic Compounds Both positive ions and negative ions must be present Both positive ions and negative ions must be present The number of cations and anions must be such that the net charge is zero The number of cations and anions must be such that the net charge is zero

7. Slide 7 Common Simple Cations and Anions CationName AnionName* H 1+ hydrogen H 1- hydride Li 1+ lithium F 1- fluoride Na 1+ sodium Cl 1- chloride K 1+ potassium Br 1- bromide Cs 1+ cesium I 1- iodide Be 2+ beryllium O 2- oxide Mg 2+ magnesium S 2- sulfide Al 3+ aluminum Ag 1+ silver * The root is given in color.

8. Slide 8 Example: Aluminum Chloride Step 1: Step 2: Step 3: 13 Step 4: AlCl 3 Criss-Cross Rule Al Cl 3+ 1- write out name with space write symbols & charge of elements criss-cross charges as subsrcipts combine as formula unit (“1” is never shown) Aluminum Chloride

9. Slide 9 Example: Aluminum Oxide Step 1: Step 2: Step 3: 2 3 Step 4: Al 2 O 3 Criss-Cross Rule Al O 3+ 2- write out name with space write symbols & charge of elements criss-cross charges as subsrcipts combine as formula unit (“1” is never shown) Aluminum Oxide

10. Slide 10 Example: Magnesium Oxide Step 1: Step 2: Step 3: 2 2 Step 4: Mg 2 O 2 Criss-Cross Rule Mg O 2+ 2- write out name with space write symbols & charge of elements criss-cross charges as subsrcipts combine as formula unit (“1” is never shown) Magnesium Oxide Step 5: MgO Simplify