Sparks CH301 WHY IS EVERYTHING SO DIFFERENT? UNIT 3 Day 1 What - - PowerPoint PPT Presentation

Sparks CH301 WHY IS EVERYTHING SO DIFFERENT? UNIT 3 Day 1

What are we going to learn today?

Think about why matter is so diverse Attractive and Repulsive Electrostatic Forces Dipole Moment

POLL: CLICKER QUESTION

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

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
• Obvious that matter is diverse. Scientists have worked

hard to develop models to explain and predict the various forms of matter.

• 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 somewhere and see for

• urselves?

Play with Scotch tape

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.

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

POLL: CLICKER QUESTION

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! WHAT CAN YOU INFER FROM THE BURET EXPERIMENT CONCERNING THE RELATIVE CHARGE ON THE LIQUIDS?

Electrons are not always equally shared

Electronegativty: Some atoms of elements have a stronger attraction for electrons than others Equal attraction – pure covalent Intermediate situation – polar covalent Characterize bonding more quantitatively using a dipole moment measurement

Electronegativity

DIPOLE MOMENT  μ μ = Q d Q = charge in coulombs d = distance separating charges electron charge = -1.60 x 10-19 C Units: Debye (D) 1 D = 3.336 10–30 (C x m)

+q

• q

DIPOLE MOMENTS OF SOME COMMON COMPOUNDS HF 1.83 D HBr 0.8 D NaCl 9.0 D (gas phase)

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

POLL: CLICKER QUESTION

Dipole Moment

GUESS THE DIPOLE MOMENT OF O=C=O

If the dipole moment of CH3Cl is 1.87 Guess the dipole moment for: CCl4

POLL: CLICKER QUESTION

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

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