WHY IS EVERYTHING SO DIFFERENT? Important Information EXAMS SHOULD BE GRADED BY MIDDAY SATURDAY HW. DEPENDS ON HOW DAY GOES.

Transcription

1 Unit3Day1-Crawford Page 1 Unit3Day1-Crawford Tuesday, October 08, :43 PM Vanden Bout/LaBrake/Crawford CH301 WHY IS EVERYTHING SO DIFFERENT? UNIT 3 Day 1 Important Information EXAMS SHOULD BE GRADED BY MIDDAY SATURDAY HW. DEPENDS ON HOW DAY GOES. CH301 Vanden Bout/LaBrake Spring 2013

2 Unit3Day1-Crawford Page 2 What are we going to learn today? Think about why matter is so diverse Attractive and Repulsive Electrostatic Forces Dipole Moment POLL: CLICKER QUESTION 1 Matter is diverse implies all of the following, EXCEPT: a) The same type of matter can exist in different phases b) Different types of matter exist in different phases at the same temperature c) Compounds exhibit different characteristic properties based on the type of elements that compose that compound d) All matter is composed of the same fundamental building blocks

3 Unit3Day1-Crawford Page 3 Work individually for 10 minutes to complete the worksheet PLEASE DO NOT TALK DURING THIS TIME WE WILL BE COLLECTING THESE WORKSHEETS! Look Around -Find three different types of matter -Articulate why you think the matter is different from a macroscopic observation and a molecular view of the substance -Obvious that matter is diverse. Scientists have worked hard to develop models to explain and predict the various forms of matter. Share: What is an important factor in different types of matter being different?

4 Unit3Day1-Crawford Page 4 Share: What is an important factor in different types of matter being different? Electrons are Important -Electrostatic Attractions and Repulsions - Forces that dominate on the molecular scale -Can we get some electrons from some where and see for ourselves -Play with Scotch tape

5 Unit3Day1-Crawford Page 5 SET UP YOUR TAPE WHEN FINISHED POLL: CLICKER QUESTION 2 Based on your observation of the tape: a) The bottom is negatively charged b) The top is negatively charged c) It is impossible to tell which is negative

6 WHAT CAN YOU INFER FROM THE BURET Unit3Day1-Crawford Page 6 Press your tape down on your desk as indicated. Gently peel the B and T tape up off the base, keeping the pieces together. When directed rip the two pieces of tape apart. Don t touch the tape to anything. Slowly bring the two pieces together. Observe Slowly bring a B tape near a neighbor s B tape. Observe. Charge a balloon. Bring each tape near the balloon to see what happens. Can you attract a liquid with a charged object? TRY IT! MOLECULES CAN CARRY A WEAK CHARGE THE GREATER THE CHARGE THE STRONGER THE ATTRACTION TO THE CHARGED ROD!

7 Unit3Day1-Crawford Page 7 MOLECULES CAN CARRY A WEAK CHARGE THE GREATER THE CHARGE THE STRONGER THE ATTRACTION TO THE CHARGED ROD! WHAT CAN YOU INFER FROM THE BURET EXPERIMENT CONCERNING THE RELATIVE CHARGE ON THE LIQUIDS? Electrons are not always equally shared Some atoms of elements have a stronger attraction for electrons than others property is called Electronegativity Characterize Bonding more Quantitatively Using a Dipole Moment Measurement Intermediate situation polar covalent Equal attraction pure covalent Electronegativity

8 Electronegativity 1 D = (C x m) Unit3Day1-Crawford Page 8 Measure the Dipole Moment DIPOLE MOMENT μ μ = Q r Units: Debye (D)

9 DIPOLE MOMENT μ μ = Q r Units: Debye (D) 1 D = (C x m) CH302 Vanden Bout/LaBrake Fall 2012 DIPOLE MOMENTS OF SOME COMMON COMPOUNDS HF 1.83 D HBr 0.8 D NaCl 9.0 D (gas phase) POLL: CLICKER QUESTION 3 Given the following dipole moments: HF 1.83 D HBr 0.8 D NaCl 9.0 D (gas phase) Unit3Day1-Crawford Page 9

10 Unit3Day1-Crawford Page 10 POLL: CLICKER QUESTION 3 Given the following dipole moments: HF 1.83 D HBr 0.8 D NaCl 9.0 D (gas phase) Which of the following is a good guess for the dipole moment of HI? a) 0.4 D b) 1.4 D c) 2.4 D d) 4.0 D Dipole Moment GUESS THE DIPOLE MOMENT OF O=C=O POLL: CLICKER QUESTION 4 If the dipole moment of CH 3 Cl is 1.87 Guess the dipole moment for:

11 POLL: CLICKER QUESTION 4 Unit3Day1-Crawford Page 11 If the dipole moment of CH 3 Cl is 1.87 Guess the dipole moment for: CCl 4 Shape Matters Go from a 2 dimensional model to a 3 dimensional shape Take a look at Cl 2 Take a look at HCl Take a look at CO 2

12 Unit3Day1-Crawford Page 12 What have we learned? Electrostatic Forces Dominate on the Molecular Level We have observed Electrostatic Forces Solids/Liquids/Gases Something to do with the Forces Depending on how the electrons are dispersed in a bond, may or may not be polar Shape matters 1 Learning Outcomes Recognize that matter is diverse and the condensed phases of matter will vary based on composition Identify polar bonds Understand the concept of the bond and a dipole Define dipole moment