December 1, Welcome Back! Homework: Read pgs DoNow: Update T.O.C Pg. 41- Chemical Equations pg. 42- Conservation Mass/Chemical Equations -Open textbook to pg. 25- Look at Figure 9 On pg. 41 Identify the elements and the number of atoms for each element in the chemical formulas listed in figure 9 (Skip water and Carbon dioxide)

What is in a Chemical formula? A combination of symbols that represents the elements in a compound. Ex: NaCl CO 2 Subscripts represent….? - the number of atoms of an element in a molecule or the ratio of elements in a compound.

What’s in a Chemical Equation? Think about what goes into a recipe? What's a recipe you know?  Ingredients are the reactants- mixed/combined together and once they are combined (chemical reaction) they produce (yield) something new, a product.  Reactants- the materials you have at the beginning of the equation  Products- the different materials you have at the end of the equation, after the reaction.

Create your own Recipe of Reactants & Products For the list of Chemical Equations make a “recipe” card that includes: -The written equation, label the reactant side and product side -List the elements or formula(s) on the reactant side of the equation, and the number of atoms for each EX: Reactants: H Hydrogen atoms, 2 Oxygen atoms -Repeat for the product side of the equation -Be creative in your description

December 2, 2014 Homework: Answer Figure 11- Problem Solving question (on pg. 27) Section 2 Review (pg. 31) problems 1,2 all on binder pg. 42 Do Now:  Agenda- Write H.W.  Open textbook to pg. 26- Look at Figure 10-  Read the caption and observe the diagram- Answer the question on pg. 42 of your binder:  How do you know that mass has been conserved in the reaction?

How Do We Know Mass Was Conserved? The mass of the reactants (14 grams + 8 grams) equals the mass of the products (22 grams). How can we define the Law of Conservation of Mass in terms of Reactants and Products? The mass before the reaction = the mass after the reaction. ( Reactants) (Products)

Model Conservation of Mass Lego Lab Activity: Build a model that demonstrates that the Law of Conservation of Mass is true in chemical equations.

Challenge equation -Ask for additional Lego's Build a model and follow the same procedure for the equation below: Fe 2 O 3 + C  Fe + CO 2  What are your results?  Why do you think you received these results?  What do you think you can do to the equation so it follows the Conservation of mass?

Conclusions… What were your results?

Assess Yourself! Write the # on your paper Which statement BEST describes you after this activity? 1) I’m a Novice: -I’m just starting to learn this, and I really don’t understand it yet 2) I’m an apprentice: -I’m starting to get it, but I still need someone to coach me through it. 3) I’m a Practitioner: - I can mostly do it by myself, but I sometimes mess up or get stuck. 4 ) I’m an Expert: I understand it well, and I could thoroughly teach it to someone else.

One sentence summary… In a one sentence summary answer : How do the numbers of the atoms (and mass) for the reactants of a chemical equation compare with the atoms (and mass) for the products?