2. Chemistry Unit 4 Bonding

3. Why do atoms bond? -to become more stable -a full valence shell of electrons -valence shell = outside shell How do atoms bond? 2 main types of bonds 1. Ionic 2. Covalent

4. Bonding Ionic Bonds form between a metal and a nonmetal. Covalent Bonds form between two nonmetals.

5. Ionic Bonding Ion - a charged particle *if an atom loses an e -, it is a (+) ion (now has more p + than e - ) *if an atom gains an e -, it is a(-) ion (now has more e - than p + )

6. Ionic Bonds When an ionic bond forms, one atom gains electrons and the other atom loses electrons. The ions are oppositely charged and therefore are attracted to each other. An ionic bond forms from a transfer of electrons. Both atoms become more stable ions by filling their outside electron shells.

7. Ionic bonding continued Example: e-e- NaCl e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- 11 12 17 18 e-e-

8. Ionic bonding continued Example: e-e- Na Cl e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- 11 12 17 18 e-e- Na +1 Cl -1 NaCl Sodium chloride

9. Covalent Bonding Atoms share pairs of electrons to fill the valence shell HCl 1 0 17 18 e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- HCl Hydrogen chloride