Mid-Term ReviewDay #3—Valence Electrons and Mixed Review!

Do Now: HW, Reference Tables, and Calculator Out.

Complete Do Now on handout

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.

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?

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?

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 CaCl2. [1]

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 CO2. [1]

1) 2 2) 2 3) 2 4) 4 8) 4 9) 2 10) +511) ethane

5) 3 6) 2 7) 2 12) D 13) 4

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

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

16) Si = ground 2-8-4 excited 2-7-5 or 2-8-3-117) Mass = protons + neutrons Al = 13 + X = 27 amu = 14 neutrons18) 2KClO3 2KCl + 3O2

19) decomposition

Bonding HW

Summary

• Explain how valence electrons are related to bonding?