The Octet rule of bonding Rule of eight The Octet rule of bonding 1

ChemCatalyst Only certain combinations of elements result in the formation of compounds. Li, lithium, will react with F, fluorine, to form LiF, but it won’t form LiF2 or LiF3. Mg, magnesium will react with F to form MgF2, but it won’t form MgF or MgF3. Explain what you think is going on. Unit 1 • Investigation V 2

The Big Question What determines how two elements will combine to a stable compound? Unit 1 • Investigation V 3

Rule of eight Octet Rule: Ionic compounds tend to form from atoms that together have a total of 8 (or a multiple of 8) electrons in their outermost (valence) shells. This gives each ion a valence electron configuration identical to a noble gas and makes them very stable. 2nd requirement: There must be at least 1 cation and 1 anion in each compound Unit 1 • Investigation V 4

AL2O3

Handout instructions Name on handout Fill out all empty spaces in chart (valence electrons, Compound formula) Write Cation, Anion name (Noble gas configuration) in 1st and 3rd columns

total # of valence electrons Activity Element 1 (metal, cation) # of valence electrons Element 2 (nonmetal, anion) # of valence electrons compound total # of valence electrons Na 1 F 7 NaF sodium fluoride 8 Mg O MgO magnesium oxide 2 Cl MgCl2 magnesium chloride 16 Ne neon Be BeF2 beryllium fluoride Unit 1 • Investigation V 7

total # of valence electrons Element 1 (metal, cation) # of valence electrons Element 2 (nonmetal, anion) # of valence electrons compound total # of valence electrons MgS magnesium sulfide CaCl2 calcium chloride Na Br K Se Al N O Al2O3 aluminum oxide F Unit 1 • Investigation V 8

Check-In What elements will combine with Sr, strontium, in a one-to-one ratio? Unit 1 • Investigation V 9

Wrap-Up Elements react to form compounds in such a way as to result in 8 electrons in their outermost (valence) shell (or a multiple of eight). Compounds with eight valence electrons are very stable. Noble gases already have eight valence electrons and don’t combine with other elements to make new compounds. They are already very stable. Unit 1 • Investigation V 10

Octet Rule and its use in forming compunds Second part of lab Octet Rule and its use in forming compunds 11

DISTRIBUTE THE SALTY EIGHT CARDS Discuss information shown on the card DISTRIBUTE THE SALTY EIGHT CARDS

Definition of a salt An ionic compound formed by acting a acid with a base Examples include NaCl, KCl, CuSO4

ChemCatalyst List the compounds you can make with pairs of cards of two different elements. List the compounds you can make with three cards and only two different elements. Unit 1 • Investigation V 14

The Big Question What salts can be formed by combining a metal and a non-metal? Unit 1 • Investigation V 15

You will be able to: Apply the octet rule. Unit 1 • Investigation V 16

Procedure Divide up into groups of 4 Get a deck of salty eight cards Play game

Activity Rules for Salty Eights: The point of the game is to make compounds and to be the first to play all of the cards in your hand. These compounds can have two or three or more cards in them, but they can only have two different elements. The game ends when a player uses up all of the cards in his or her hand making compounds. (cont.) Unit 1 • Investigation V 18

Shuffle the deck as best as possible. Deal eight cards to each player. (Game Sequence) Shuffle the deck as best as possible. Deal eight cards to each player. The player to the left of the dealer plays first. Using at least two cards from your hand, try to make one compound – the valence electrons must add up to eight or a multiple of eight. You must have at least one pink card and one blue card with each compound noble gases—green cards—are an exception and can be played singly (cont.) Unit 1 • Investigation V 19

(cont.) You must play every turn. In other words you must make one compound each time it is your turn. If you cannot make a compound you must draw from the draw pile until you can put down a compound. When you form a compound during your turn simply place those cards on the table in front of you. (cont.) Unit 1 • Investigation V 20

A player gets 20 points for going out first. (cont.) Play proceeds around the circle until a player uses up all of his or her cards. A player gets 20 points for going out first. Wild cards can be used as any element in that particular group (Wild cards only exist for Groups 1 and 7). The player must identify which element a wild card represents at the time it is played. (cont.) Unit 1 • Investigation V 21

Card/Play Values Card/ Card Combination/ Play option Point value Place a noble gas card 5 points Form a compound out of 2 cards 10 points Form a compound out of 3 cards 40 points Form a compound out of 4 cards 70 points Form a compound out of 5 cards 100 points Going out first (have formed compounds with all cards) 20 points

Scoring Scoring: Every compound played on the table is worth points. The cards left in a person’s hand are subtracted. Any player with cards left in his or her hand must count up the number of valence electrons and subtract them from his or her total. (cont.) Unit 1 • Investigation V 23

Metal Cation Nonmetal Anion Compound Formula Compound Name Point value Total Unit 1 • Investigation V 24

Must complete chart as proof Tournament time Must complete chart as proof

Check-In Which of the following compounds are likely to form? (a) Na2S (b) K2Mg (c) AlBr2 (d) Na3N (e) OCl (f) CaMgO2 Unit 1 • Investigation V 26

Wrap-Up Ionic compounds tend to form from atoms that together have a total of 8 (or a multiple of 8) electrons in their outermost (valence) shells Compounds with eight valence electrons are highly stable. Noble gases already have eight valence electrons and don’t combine with other elements to make new compounds. They are already highly stable. Unit 1 • Investigation V 27