Name _____________________ Date _________ Period ____

1. Name _____________________ Date _________ Period ____ Valence Electron Interaction and Charges

2. The Role of Electrons in Bonding • The sharing or transfer of electrons is what holds atoms together in a compound • Typically, only the electrons in the outer energy level are used for bonding. • These electrons are called Valence Electrons • The outer energy level is called the Valence Shell

3. Comprehension Check • How many electron shells does phosphorus have? • 3 • How many valence electrons does phosphorus have? • 5

4. PWYR – Valence Schmalence • tin • 4 • arsenic • 5 • strontium • 2 • bromine • 7 • sodium • 1 • tellurium • 6 • gallium • 3 • krypton • 8

5. Bonding • Ionic Bonds – Results from the complete transfer of electrons • Results in a formation of two charged atoms called ions • The atom that gains electrons becomes negatively charged and is called an anion • The atom that loses electrons becomes positively charged and is called a cation

6. Octet Rule • Octet Rule: atoms want to have a full valence shell (8 valence electrons) • Atoms react with one another in an attempt to gain or lose electrons to fill their valence shell • During a reaction, electrons can be shared or completely transferred • Two options • Gain electrons to fill valence shell • Lose electrons to reveal full shell below outer shell (outer shell)

7. Oxidation Numbers • Oxidation Numbers tell us how many electrons an atom is willing to lose or gain • Positive oxidation numbers indicate that the atom can lose that many electrons • Negative oxidation numbers indicate that the atom can gain that many electrons • Some atoms have more than one possibility • Transition Metals

8. Alkali and a Halogen Valence Electrons Missing Electron Extra Electron

9. valence electron = 1 • Easier to give away for full valence shell • Cation = positive -getting ride of negative particle • Charge = +1 • valence electron = 7 • Easier to take in for full valence shell • Anion = Negative - taking in negative particle • Charge = -1

10. Periodic Table • Groups have same valence electrons • Same oxidation number 8 1 7 0 -1 2 +1 5 3 4 6 -3 -2 +2 +3 +/-4

11. Comprehension Check- To Gain or Not to Gain • Nitrogen  • Beryllium  • Xenon  • carbon  • Oxygen  • Lithium  • Chlorine  • Boron  Gain 3 Lose 2 None Gain/Lose 4 • Gain 2 • Lose 1 • Gain 1 • Lose 3