Catalyst  1. If you did not do so yesterday, write a short reflection (2 sentences). This can be about anything! If you’re stuck, tell me one thing you’re looking forward to this year, what you did over winter break, or what your new year’s resolutions are.  2. How many total atoms are in the compound NH 4 (CO 3 ) 2 ?  3. How many atoms are in the compound (NH 4 ) 3 F 2 ?  4. What is the atomic number for bromine (Br)? What is the mass number?

Today’s Agenda 5 min Catalyst 10 min Semester Focus and Changes 10 min Chemical Equations 10 min T-Charts 10 min Balanced or No? 5 min Exit Slip

Some Changes and Reminders  Welcome to second semester!  It is our goal to constantly improve, and to do this, we need to remind ourselves of the things we did well last semester as well as the things we need to change

Goal: High Quality Work  Homework assigned on Monday  Due Wednesday  Stamp checked  Homework assigned on Wednesday  Due Friday  Packet handed in  Goal– high quality work; be careful and follow all directions!  No copying

Goal: Less Late Work  Reminder of late work policy  1 day to 1 week late = Half credit on homework  After 1 week late = no credit  Excused absences will be given extra time  New– THERE WILL BE NO OPPORTUNITIES TO REDO OR COMPLETE LATE PACKETS  New- Website available for you to print packets if you’ve lost one  New– Extra credit will consistently be available to everyone  Let’s see how this will work

Extra Credit  10 questions will be available for each objective we cover in class  Each of these sections done correctly will earn 12 extra homework points (equivalent to a ‘B’ on a homework assignment)  These may be turned in up until we take the unit test for that unit  Extra credit must be requested  If you want it, ask Professor Myers!

Goal: More Participation  More participation… from more people  Methods:  Raise your hand!  Popsicle sticks (look to your seat number)  Cold calling  Participation points will be given for all three

Goal: 85% Averages  Chemistry EOC happens in May  Our next two units will be THE MOST IMPORTANT on the EOC  85% class averages on quizzes and tests will help us get to Proficient and Advanced  We will also be looking back to previous units to remind ourselves of old objectives.  Don’t just learn to get done with the test. Learn to understand!  Be prepared… Be present… Be persistent… and you will Be proficient!

Today’s Agenda 5 min Catalyst 10 min Semester Focus and Changes 10 min Chemical Equations 10 min T-Charts 10 min Balanced or No? 5 min Exit Slip

Unit 5  Unit 5: Chemical Equations and Reactions

EQUATIONS A chemical equation is basically a “sentence” that tells what happened in a chemical reaction For example: 2NaCl + Br 2  2NaBr + Cl 2 or Hg + O 2  HgO Law of Conservation of Mass: When something goes through a chemical reaction, you cannot lose or create mass/energy. This means that whatever we start with, we have to end with the same amount. If I start with 10g of something, I need to end with 10g of something else.

Reactants and Products There are two sides of an equation: the reactants and the products. The reactants are on the LEFT, products are on the RIGHT. 2NaCl + Br 2  2NaBr + Cl 2 Reactants Products

CHECK UP 1. Reactants are on the ___________ 2. Products are on the ___________ 3. According to the Law of Conservation of Mass, we have to have (same/different) amount of reactants and products

Today’s Agenda 5 min Catalyst 10 min Semester Focus and Changes 10 min Chemical Equations 10 min T-Charts 10 min Balanced or No? 5 min Exit Slip

Why Counting Atoms Matters… How can we tell if a reaction is obeying the Law of Conservation of Mass? It has to have the same number of each atom on the reactants side of the equation and the products side. We need a skill that we’ve used before…. counting the number of atoms in a compound! 2 MgCl 2 has 2 Mg and 4 Cl

Why Counting Atoms Matters… How can we tell if a reaction is obeying the Law of Conservation of Mass? It has to have the same number of each atoms on the reactants side of the equation and the products side. We need a skill that we’ve used before…. counting the number of atoms in a compound! 2 MgCl 2 has 2 Mg and 4 Cl Before, we only did this for single compounds, now it will be in an entire equation

Creating a T-Chart 2NaCl + Br 2  2NaBr + Cl 2 Steps to check for a balanced equation: 1. List all elements down the middle Na Br Cl Leave some space here!

Creating a T-Chart 2NaCl + Br 2  2NaBr + Cl 2 2. Count the number of atoms of each element on the reactant side and then the products side *Coefficients only count for the compound they are next to Na Br Cl 2_

T-Chart Practice  AgNO 3 + NaCl ----> AgCl + NaNO 3 Ag O N 1_ 3_ 1_ 3_ Na 1_ Cl 1_

Today’s Agenda 5 min Catalyst 10 min Semester Focus and Changes 10 min Chemical Equations 10 min T-Charts 10 min Balanced or No? 5 min Exit Slip

Key Points!  The law of conservation of mass states that in a chemical reaction, mass will be conserved (meaning it will be the same before and after a chemical reaction)  When we apply the law of conservation of mass to a chemical equation, this means that the reactants and products must have the same number of each element

Unbalanced Equations  A skeleton equation is one that tells us the compounds/elements that are part of a reaction, but it may not obey the law.  Which law?  A balanced equation has the same number of each element for both the reactants and the products.

Balanced or No?  HCl + NaOH ----> H 2 O + NaCl

Balanced or No?  2 Na + Cl 2  2NaCl

Balanced or No?  KNO 3  KNO 2 + O 2

Balanced or No?  2 C 2 H O 2  4 CO H 2 O

Balanced or No?  2 K + 2 H 2 O  2 KOH + H 2

Today’s Agenda 5 min Catalyst 10 min Semester Focus and Changes 10 min Chemical Equations 10 min T-Charts 10 min Balanced or No? 5 min Exit Slip

1. In order to obey the law of conservation of mass, the reactants and products side must have _______number of atoms. a. Different b. The same 2. H 2 CO 3 → H 2 O + 2 CO 2 Is this equation balanced? Make a T-chart if necessary. 3. True or false: It is possible for water and oxygen go through a chemical reaction, and at the beginning, there is 5g and at the end there are 4g. 4. In the following chemical equation, what are the reactants? Mg + O 2  2 MgO