1. Mid-Term Review Day #3—Valence Electrons and Mixed Review! Do Now: HW, Reference Tables, and Calculator Out. Complete Do Now on handout

4. Valence Electrons are the electrons found in the outermost shell of an atom. Lewis structures depict valence electrons as dots surrounding the element symbol. Sample question: Draw the Lewis electron dot diagram for Fluorine pictured here.

5. Valence Electrons are found as the last number in the electron configuration found on the periodic table. Sample question: How many valence electrons do the atoms in Group 16 have?

6. Atoms become stable and unreactive with 8 valence electrons (or 2 for H, He and Li). Noble gases (group 18) all have 8 valence electrons. Every other atom gains, loses or shares electrons to reach 8 valence electrons. Sample question: When nitrogen shares electrons to reach 8 valence electrons, which noble gas will it share an electron configuration with?

7. Ionic bonds form when metals transfer their valence electrons to non-metals. This allows both atoms to have 8 valence electrons. Sample question: Explain, in terms of electrons, the type of bonding between Ca and Cl in CaCl 2. [1]

8. Covalent bonds form when non-metals share valence electrons. This allows all bonding atoms to have 8 valence electrons. Sample question: Explain, in terms of electrons, the type of bonding between C and O in CO 2. [1]

9. 1)22) 23) 24) 48) 49) 210) +5 11) ethane

10. 5) 36) 27) 212) D13) 4

11. They were deflected because the nucleus was positive and alpha particles were positive. Like charges repel!

12. H = 2 mol x 1.0 g = 2 g O = 2 mol x 16.0 g = 32 g 32 + 2 = 34 g/mol

13. 16) Si = ground 2-8-4 excited 2-7-5 or 2-8-3-1 17) Mass = protons + neutrons Al = 13 + X = 27 amu = 14 neutrons 18) 2KClO 3  2KCl + 3O 2 19) decomposition

14. Bonding HW

18. Summary Explain how valence electrons are related to bonding?