BELL WORK: Answer the following questions. How many atoms? 2CaOH How many hydrogen atoms? 2C2H(OH)2 What’s the chemical formula for Trinitrogen dioxide? How many elements are in the following? 6 6 N3O2 3

This is what we know so far… Compounds are formed from elements. Compounds are made from chemical reactions. Atoms make up compounds (or molecules). A subscript shows how many atoms of a particular element there are in a compound. Coefficients are multiplied by each subscript.

Show your speed… How many oxygen atoms? OH3 1

Show your speed… How many hydrogen atoms? 2 OH3 6

Show your speed… How many total atoms? 3 OH3 12

Show your speed… How many calcium atoms? Ca2Cl4 2

Show your speed… How many total atoms? 3 Ca2Cl4 18

Show your speed… How many chlorine atoms? 2 Ca4Cl 2

Show your speed… How many oxygen atoms? 2 H2O2 4

Counting Atoms with Subscripts, Coefficients…and now… Parentheses! “Multiply parentheses” BEFORE you multiply the coefficient to everything. 3 Na(O2H)2 Na = O = H = 7 x 3 = 21 1 2 4 1 2

Now you try… 2 Ca(H2)2 Ca = H = 2 8 10

Now you try… Ca3(H4)2 Ca = H = 3 8 11

Now you try… 2 Na(O2H)2 Na = O= H = 2 8 4 14

WAR! Each member of your group will have a different color card set. All at once, each member (without looking) will randomly flip a card over (face up now). Look at all the cards. Who has the highest amount of oxygen atoms? The winner of that round will take all those cards. At the end, the person with the most cards in their pile is the winner! If you have time for another game, play it with TOTAL ATOMS instead of OXYGEN.