2. The Formation and Nature of Ionic Bonds DO Now: Standard I&E: 2a, 2c, 7b Terms: 215 Mastering Concepts: 236 (51-53) Practice Problems: 217(7-9) Homework: Cornell Notes: 8.2 Section Assessment: 220(12-17) Mastering Problems: 236 (67-73) 8 Stamps

3. Section 8-2 Section 8.2 Ionic Bonds and Ionic Compounds Describe the formation of ionic bonds and the structure of ionic compounds. compound: a chemical combination of two or more different elements Generalize about the strength of ionic bonds based on the physical properties of ionic compounds. Categorize ionic bond formation as exothermic or endothermic.

4. Section 8-2 Section 8.2 Ionic Bonds and Ionic Compounds (cont.) ionic bond ionic compound crystal lattice electrolyte lattice energy Oppositely charged ions attract each other, forming electrically neutral ionic compounds.

5. Section 8-2 Formation of an Ionic Bond The electrostatic force that holds oppositely charged particles together in an ionic compound is called an ionic bond.ionic bond Compounds that contain ionic bonds are called ionic compounds. ionic compounds Binary ionic compounds contain only two different elements—a metallic cation and a nonmetallic anion.

6. Section 8-2 Formation of an Ionic Bond (cont.)

7. Section 8-2 Properties of Ionic Compounds Positive and negative ions exist in a ratio determined by the number of electrons transferred from the metal atom to the non-metal atom. The repeating pattern of particle packing in an ionic compound is called an ionic crystal.

8. Section 8-2 Properties of Ionic Compounds (cont.) The strong attractions among the positive and negative ions result in the formation of the crystal lattice. A crystal lattice is the three-dimensional geometric arrangement of particles, and is responsible for the structure of many minerals.crystal lattice

9. Section 8-2 Properties of Ionic Compounds (cont.) Melting point, boiling point, and hardness depend on the strength of the attraction.

10. Section 8-2 Properties of Ionic Compounds (cont.) In a solid, ions are locked into position and electrons cannot flow freely—solid ions are poor conductors of electricity. Liquid ions or ions in aqueous solution have electrons that are free to move, so they conduct electricity easily. An ion in aqueous solution that conducts electricity is an electrolyte.electrolyte

11. Section 8-2 Properties of Ionic Compounds (cont.) This figure demonstrates how and why crystals break when an external force is applied.

12. Section 8-2 Energy and the Ionic Bond Reactions that absorb energy are endothermic. Reactions that release energy are exothermic.

13. Section 8-2 Energy and the Ionic Bond (cont.) The energy required to separate 1 mol of ions in an ionic compound is referred to as the lattice energy. lattice energy Lattice energy is directly related to the size of the ions that are bonded.

14. Section 8-2 Energy and the Ionic Bond (cont.) Smaller ions form compounds with more closely spaced ionic charges, and require more energy to separate. Electrostatic force of attraction is inversely related to the distance between the opposite charges. The smaller the ion, the greater the attraction.

15. Section 8-2 Energy and the Ionic Bond (cont.) The value of lattice energy is also affected by the charge of the ion.

16. Naming Ionic Compounds Rules 1.Name Cation 2.Use Roman Numerals if the metal is a transition metal (Exceptions: Zn, Ag, Al) 3.Name the Anion (It may be a polyion) 4.Add the -suffixes: -ide = salts comprised of only two elements; – -ate, -ite = compounds containing a (usually metal) cation ion and a complex anion (usually involving oxygen); 15

19. Examples: From Name to Formula 1.Sodium oxide: Na +1 O 2- Na 1+ Na 2 O 2. Magnesium nitride: Mg 2+ N 3- +6 -6 Mg 3 N 2 18

20. Examples: From Name to Formula 3. Iron III chloride Fe +3 Cl- Fe +3 Cl - Cl - Cl - = FeCl 3 19

21. Practice Problems: 217 (7-11) Explain the formation of the ionic compound composed of each pair of elements. 7. Sodium and nitrogen 8. Lithium and oxygen 9. Strontium and fluorine 10. Aluminum and sulfur 11. Cesium and phosphorus 20

22. Practice Problems: 217 (7-11) Explain the formation of the ionic compound composed of each pair of elements. 21 7. Symbol Group #/valence electrons Easier to lose or gain electrons to satisfy the octet rule Charge SodiumNitrogen NaN 1e5e Lose 1eGain 3e Na +1 N -3 Na 3 N

23. Practice Problems: 217 (7-11) Explain the formation of the ionic compound composed of each pair of elements. 22 8. Symbol Group #/valence electrons Easier to lose or gain electrons to satisfy the octet rule Charge LithiumOxygen LiO 1e6e Lose 1eGain 2e Li +1 O -2 Li 2 O

24. Practice Problems: 217 (7-11) Explain the formation of the ionic compound composed of each pair of elements. 23 9. Symbol Group #/valence electrons Easier to lose or gain electrons to satisfy the octet rule Charge StrontiumFluorine SrF 2e7e Lose 2eGain 1e Sr +2 F -1 SrF 2

25. Practice Problems: 217 (7-11) Explain the formation of the ionic compound composed of each pair of elements. 24 10. Symbol Group #/valence electrons Easier to lose or gain electrons to satisfy the octet rule Charge AluminumSulfur AlS 3e6e Lose 3eGain 2e Al +3 S -2 Al 2 S 3

26. Practice Problems: 217 (7-11) Explain the formation of the ionic compound composed of each pair of elements. 25 11. Symbol Group #/valence electrons Easier to lose or gain electrons to satisfy the octet rule Charge CesiumPhosphorus CsP 1e5e Lose 1eGain 3e Cs +1 P -3 Cs 3 P