Ch. 6 Bonding

1. Ch. 6 Bonding 6.3 Ionic Bonding

2. Ionic Compounds • ionic bonds do NOT form molecules • chemical formulas for ionic compounds represent the simplest ratio of ion types • made of anions and cations

3. Ionic Compounds • combined so that positive charges balance negative charges • crystalline solid • formula of ionic compound depends of the charges of the ions combined

4. Binary Ionic Compounds • Because positive charges must balance negative charges, use criss-cross method to make formulas. Write the formula for aluminum oxide.

5. Binary Ionic Compounds If you don’t like criss-cross, use algebra. Write the formula for barium sulfide.

6. Formation • attractive forces: • oppositely charged ions (main attraction) • nuclei and electron clouds of adjacent ions • repulsive forces: • like-charged ions (main repulsion) • electrons of adjacent ions

7. Formation • distance between the ions creates a balance between those forces • ions minimize their PE by combining in an orderly arrangement called a crystal lattice

8. Formation Specific lattice pattern created depends on: • charges of ions • determines number of electrons transferred • determines the ratio of ions • size of ions • larger ions need more space

9. Lattice Energy • energy released when separate gaseous ions bond to form ionic solid or the energy absorbed to break the bonds between ions • the larger the amount of energy, the stronger the bond • more electrons transferred or smaller ions leads to a larger lattice energy

10. In each of the following pairs of compounds, identify the one with the higher lattice energy • KCl, CaS • LiF, NaCl • Fe2O3, MnO2 • CaO, CaCl2