polarity and properties - weebly

POLARITY and

PROPERTIES

Turn in HW before class

Objectives

◻ Identify bond strengths based upon type of bond.

◻ Define polarity

◻ Apply VSEPR theory to predict the overall polarity of a molecule.

◻ Predict the properties of a molecule based on the type of molecule (Ionic, NPC, PC, Metallic)

WARM-UP:

Draw and predict the shape of the following:

(1) H2S

(2) CBr4

HOMEWORK CHECK

N/A

HOMEWORK REVIEW: ◻ VSEPR THEORY PRACTICE WORKSHEET

IDENTIFY BOND STRENGTHS BASED UPON TYPE OF BOND

Covalent Bond - RECALL

Bonds are formed by SHARING electrons

If the 2 atoms share equally (usually the 2 atoms are identical) the bond is Non Polar Covalent NPC

If the 2 atoms share unequally the bond is Polar Covalent PC

https://www.youtube.com/watch?v=_M9khs87xQ8

What Does This Represent???(Think Electronegativity!!)

Bonds Type and Bond Strength

STRONGESTNetwork Solids – Covalent “Lattice”

DiamondsMetallic and Ionic - Lattice

Ag-Ag, Alloys: Cu-ZnNaCl

Polar CovalentH2O, NH3

NonPolar CovalentO2, H2, CO2

ADD TO YOUR NOTES !! MEMORIZE THIS !!

Bonds length and strength!

Covalent Bonds – have more variety⬜Triple Bonds – shortest and strongest

⬜Double bonds

⬜Single bonds - longest and weakestADD TO YOUR NOTES !!

MEMORIZE THIS !!

Have You Ever Wondered????

Why Oil and Water don’t mix?

Why water is a LIQUID at room temperature?

Why Oxygen is a gas at room temperature?

Why salt water can conduct electricity?

DEFINE POLARITY –Lecture

Polarity

Polarity is defined as the unequal distribution of electrons or an ASSYMETRICAL (uneven) DISTRIBUTION of CHARGE

POLAR BONDS vs. POLAR MOLECULES

POLAR BONDS Nonpolar bonds have an even distribution of charge and thus no charged poles (ends).

Polar bonds are present whenever the two atoms bonded are NOT identical

NonPolar to Polar to Ionic

POLAR MOLECULES

Assymetricalcharge over the entire molecule

WATER IS POLAR

Can NONPOLAR moleculeshave POLAR bonds?

YES!!

“BONDS” occur between 2 ATOMS – when the 2 atoms bonded are DIFFERENT the BOND is POLAR

“MOLECULES” are polar if – There is a lone pair on the central atom OR If the atoms bonded to the central atom are

NOT identical

APPLY VSEPR THEORY TO PREDICT THE OVERALL POLARITY OF A MOLECULE.

How do you know if a molecule is polar?FILL IN THE MISSING NOTES

◻ Step 1: Draw Lewis Structure & Determine the shape

◻ Step 2: Predict the polarity of the molecule based on the following:

-- If the molecule has at least one ______ ______ on the central atom

-- If there are _____ or more different types of _______

MEMORIZE THIS !!■ Ex. CH4 (NonPolar) vs. CH2F2 (Polar)

LEARNING TEAMS

Take the following:◻Notebook◻Pen/Pencil◻Reference Tables

Examples – Work As A Team

Use your white boardDraw the Lewis Dot StructureFollow the POLARITY FLOWCHART to determine

polarity

⬜ NH3

⬜ CH2O

⬜ CO2

You Try - Work Independently

Determine if the following molecules are polar or non-polar.

◻ NF3

◻ SO2

◻ CH2I2

PULLING IT ALL TOGETHER

◻ Go to Molecular Geometry Exploration and complete the last 2 columns

PREDICT THE PROPERTIES OF A MOLECULE BASED ON THE TYPE

(IONIC, NPC, PC, METALLIC)

Copy this chart into your notes and complete as you read the next few slides

Type of Bond Conduct

ElectricityDissolve

In water?

State at Room

Temp

IONIC

METALLIC

POLAR Cov.

NON-POLAR

Cov.

Properties of Ionic Substances

◻ Hard

◻ Brittle

◻ A solid at room temperature

◻ Very high melting points (≈800C)

◻ Very high boiling points

◻ Soluble in water (think SALT)

◻ Conduct electricity when dissolved in water or as a liquid.

Properties of Metals

◻ Shiny

◻ Solid at room temperature.

◻ high melting point (≈1000oC) ***

◻ high boiling point ***◻ Insoluble in water (does your gold necklace wash

away when you shower?)

◻ Conduct electricity

◻ Malleable and ductile (think COPPER)

*** Which element is an exception??

Properties of Polar Molecules

◻ Typically a liquid at room temperature.

◻ Low melting points (≈20oC)

◻ Medium boiling points

◻ Soluble in water (think SUGAR)

◻ Not a of conductor electricity

Properties of Non-polar molecules

◻ Odorous liquid or a gas at room temperature.

◻ Very low melting (≈-100oC)

◻ Very low boiling points

◻ Usually Insoluble in water

◻ Not a conductor of electricity.

Here’s What You Should Have Learned

Type of

Bond

Conduct

ElectricityDissolve State at Room

Temp

IONIC Y Y SolidMETALLIC Y N Solid

Except Hg

POLAR Cov. N Y Odorous

liquids

NON-POLAR

Cov.N N and gases

MEMORIZE THIS !!

Steps for determining properties.

◻ Step 1: Draw the Lewis structures

◻ Step 2: Predict the shape

◻ Step 3: Use the Polarity Flow chart to predict the polarity

◻ Step 4: Use polarity to determine properties

Given CO2

Work Together To Answer The Following Questions:

◻ What is the overall shape?

◻ Using this shape, what type of bond is present?

Ionic, Metallic, Polar or Nonpolar?

◻ Given the shape, determine the following:⬜ What is the state of matter at room temp?

⬜ Will it conduct electricity

⬜ Will it dissolve in water?

Check Your Answers On The Next Slide

HOMEWORK

Complete Bond type/Shape/Properties Chart – see next slide

QUIZ Tomorrow (Lewis Structures / Shapes)

UNIT 4 TEST – Fri Oct 12

Bond type/Shape/Properties HW-Draw complete chart

Compound Type of Bond?

(I, M, PC, NPC)

Shape State of

Matter

Conduct

Electricity?

Dissolve in

Water?

CO2 NPC Linear Gas No No

PCl3

H2O

CF4

MgCl2

Cl2

CH2Cl2

NH3

AlCl

Objectives (Today You’ve Learned How To….)

◻ Identify bond strengths based upon type of bond.

◻ Define Polarity

◻ Apply VSEPR theory to predict the overall polarity of a molecule.

◻ Predict the properties of a molecule based on the type of molecule (Ionic, NPC, PC, Metallic)