Do Now – name and count the atoms Carbon: 1 Oxygen: 2 2. 2NaAu(CN)2 Sodium: 2 Gold: 2 Carbon: 4 Nitrogen: 4 3. 3N(O2H2)2 Nitrogen: 3 Oxygen: 12 Hydrogen: 12 Example: BaBr2 Barium: 1 Bromine: 2

Homework and Announcements USA TestPrep (due Mondays) Finish independent practice problems (slide 23) Summary Test Averages – A List 

Title: Endo vs Exo L.O. SWBAT determine if a reaction is endothermic or exothermic.

Chemical Bond Review – Polar vs Non Polar https://www.youtube.com/watch?v=7DjsD7Hcd9U

REACTANTS  PRODUCTS Reactants: Will be changed into new substance. What you start with. Products: New Substance formed What you end up with.

Thermal Energy: “Movement of Heat” FLOWS: warmer matter to cooler matter. Chemical Reactions: Released or absorbed Higher temperature = faster particles = more thermal energy

Which of the following has more thermal energy? A melted chocolate bar. A solid chocolate bar. Why? Higher temperature = higher thermal energy

Exothermic vs Endothermic https://www.youtube.com/watch?v=L-G7pLufXAo

Heat is absorbed (heat is taken in) Heat is a reactant. Endothermic change: Endo - In Thermos - heat Example: Ice + Heat  Water (Physical change) Ca + Cu + Heat  CaCu (Chemical change) Heat is absorbed (heat is taken in) Heat is a reactant.

Heat is absorbed so the particles move faster. Which of these is endothermic? Liquid water changes to Solid ice Solid ice changes to Liquid water Why? Heat is absorbed so the particles move faster.

Heat is released (heat exits) Heat is a product. Exothermic change: Exo - Out Thermos - Heat Example: 2Mg + O2  Heat + Light + 2MgO (Chemical change) Water  Heat + Ice (Physical change) Heat is released (heat exits) Heat is a product.

Which of these is a exothermic change? Instant cold packs Instant hand warmer pack Why? Because the hand warmer is releasing heat.

Endothermic or Exothermic, Why? Pair Share Endothermic or Exothermic, Why? 1. Photosynthesis. (CO2 + H2O + Energy  O2 + Glucose) Endothermic. Energy is a reactant. 2. Fireworks exploding? Exothermic. Powder + O2  Heat + Light + Gas 3. Baking a cake? Endothermic. Batter + Heat  Cake

“Elephant Toothpaste” 2H2O2 2H2O + O2 Is this equation balanced? releases heat or absorbs heat? Is the heat a reactant or a product? Endothermic or Exothermic?

Elephant Toothpaste https://www.youtube.com/watch?v=p1eG2y2mn54

“Elephant Toothpaste” 2H2O2 2H2O + O2 Is this equation balanced? releases heat or absorbs heat? Is the heat a reactant or a product? Endothermic or Exothermic?

Fire with Science Bob https://www.youtube.com/watch?v=uvzCv32yKSc

NO YES Problem 1 Problem 2 2NaClO3  2NaCl + 3O2 + heat C3H8 + 3O2 + heat  3CO2 + 4H2O Circle the reactants Underline the products Is the equation endothermic or exothermic? Is the equation balanced? (Does it Show conservation of matter?) Circle the reactants Underline the products Is the equation endothermic or exothermic? Is the equation balanced? (Does it Show conservation of matter?) NO YES ( C:3 H:8 O:6  C:3 H:8 O: 6+4=10) ( Na:2 Cl:2 O:6  Na:2 Cl:2 O:6)

Summary – 5 minutes silent writing time When looking at a chemical equation, how do you determine if it follows the law of conservation of matter? What is the difference between endothermic and exothermic reactions? Give an example of an endothermic reaction. Give an example of an exothermic reaction.

Independent Work Name each atom found in the following compounds and determine how many atoms of each element are present: 1) CaF2 2) Be(OH)2   3) NO2 4) Al2(SO4)3 5) NH4NO3   6) S2F2 7) Na2CO3 8) CH4