Creating a Positive Learning Environment for Everyone Be respectful of your classmates Save conversation for clicker portions of lecture Put cell phones in “airplane” mode Turn off tablets Close laptops

Announcements Pre-lab due this week at the start of lab! Electronic HW #6 Type 1 due Monday, Nov. 27th at 7:00pm Electronic HW #6 Type 2 due Wednesday, Nov. 29th at 7:00pm

Exothermic: more energy leaves the system overall Endothermic: more energy goes into the system overall 2H2 + O2  2H2O 2H2O  2H2 + O2

Clicker #1 If the reactants are defined as the system, is this an endothermic or exothermic process? A) endothermic B) exothermic

Clicker #2 How would the energy diagram for this reaction look?

Example #1 Is the freezing of water an endothermic or exothermic process? (The system is underlined.) Exothermic

Clicker #3 Is the boiling of water an endothermic or exothermic process? (The system is underlined.) A) endothermic B) exothermic

Example #2 Is an activated cold pack an endothermic or exothermic process? (The system is underlined.) Endothermic

Clicker #4 Is an activated hot pack an endothermic or exothermic process? (The system is underlined.) A) endothermic B) exothermic

Clicker #5 Is a racquetball frozen by liquid nitrogen an endothermic or exothermic process? (The system is underlined.) A) endothermic B) exothermic

Example #3 Is the thermite reaction (the chemical reaction) an endothermic or exothermic process? (The system is underlined.) Exothermic

Overall goal: Atomic Structure Chemical Bonding 3D Molecular Structure Molecular Properties

Various Atomic Models Dalton: Law of Definite Proportions. (He concludes that atoms are indivisible and have mass.) J.J. Thompson: atoms emit tiny negative particles. (Therefore atoms not indivisible!) William Thompson: formulates the Plum Pudding Model. (Electrons moving in a positively charged cloud.) Rutherford: Some α-particles bounce back when shot at atoms.

Clicker #6 If alpha particles (which are the positively charged nuclei of helium atoms) bounce back when shot at atoms, what is most likely causing them to bounce away? Negatively charged particles Positively charged particles Positively OR negatively charged particles Neutral particles No particles (There is a concentration of mass with a positive charge in the atom.)

Reading Homework for Thursday Review the various atomic models in your textbook (Sections 4.3, 4.5) Read about electromagnetic radiation (Sections 11.1-11.5)