Warm Up…what do you
remember?
1. Why do bonds form?
2. What is the difference between
ionic and covalent bonds?
Warm Up…what do you
remember?
Why do bonds form?
What is the difference between ionic
and covalent bonds?
Draw the Lewis Structures and show the
behavior of the electrons.
Sodium and Bromine
Fluorine and oxygen
(you will need 2 F)
Covalent Compounds
Nonmetal bonding with another nonmetal
Electronegativity difference less than 1.67
Electrons being shared
Formation of Covalent Bond
Bond Stability
Properties of Covalent
Compounds
– low melting point
– low boiling point
– many are gas and liquid at room temp
– typically do not conduct electricity when
dissolved in water
This is due to the fact that forces of attraction
between molecules are much weaker when the
electrons are being shared.
Ionic vs covalent
Visual Concepts
Warm Up- Write the correct
formulas from the names.
1.
2.
3.
4.
5.
Copper (III) iodide
Sodium oxide
Calcium nitride
Chromium (II) oxide
Iron (III) sulfide
When do we need to use Roman Numerals
in the name of an ionic compound?
Discuss Signs…
Draw the MO diagram for
Carbon and Oxygen…
What do the electrons do??
Do we need to worry about
covalent compounds being
neutral?
Are the electrons being
shared equally??
Polar or Nonpolar?
Nonpolar- electrons are
shared equally.
Polar- electrons are not
shared equally.
Octet Rule
• Noble gases: have filled valence shells =
2 (He) or 8 e• Octet Rule tells us that chemical
compounds tend to form so that atoms
obtain an octet of e- in its highest energy
level.
Visual Concepts
Lewis Structure Rules
Add up total number of valence ePick central atom and create the bonds
Surround the adjacent atoms.
Put extra electrons on the central atom.
Beg, borrow or steal so that all the atoms are
stable (have a complete octet).
6. Make sure the number of valence e- you
started with are the number you used!
1.
2.
3.
4.
5.
Lets do…
CH4
SiF4
NCl3
Draw the Lewis Structures for
the following molecules…
CH3F
SiCl4
How many shared electrons?
How many unshared electrons?
Are the electrons shared equally?
Dipoles
Indicate polarity- dipole points to the most
electronegative atom!
Show the unequal distribution of charge
Exceptions
• Boron trifluoride BF3
• PF5 and SF6 can expand the shell and
share more electrons. (10 and 12
respectively)
Diatomic Molecules
You must memorize these!!
H2 N2 O2 F2 Cl2 Br2
I2
(At2)
Magnificent 7—
I won’t hold you responsible for astatine,
just know that trends in a group apply!
Naming Covalent Compounds
Covalent compounds are molecules or
molecular compounds…
Indicate the number of each atom using
prefixes…..
…change the end of the name to “ide”
Covalent Prefixes
Use the prefixes!
1- mono
2- di
3- tri
4- tetra
5- penta
Examples: NO
SiCl4
6- hexa
7- hepta
8- octa
9- nona
10- deca
Practice
Formulas to names
1. SO3
2. ICl3
3. PBr5
4. CO
5. CO2
Names to formulas
1. Carbon tetrachloride
2. Dinitrogen monoxide
3. Dinitrogen tetroxide
4. Phosphorus triiodide
5. Sulfur heptafluoride
Homework- You can do these!
H2Se
CH2Cl2
Silicon Tetrachloride
HCl
Fluorine
CH4
NH3
Silicon Tetrachloride
Chlorine
Warm Up- Thursday
Write the names from the formulas…
1. BaSO4
2. MnO4
3. SiO2
4. PO
5. NiPO4
Questions on Homework?
Lewis Structure WS…
Naming Covalent Compounds WS
Forming Multiple Bonds
CO2
N2O
Multiple Covalent Bonds
• Bond length and strength
– Triple bonds are the shortest (pm) and have
the most Energy (kJ/mol)
– Single bonds are the longest (pm) and have
the least amount of Energy (kJ/mol)
Sigma s and Pi p bonds
• Sigma (s) bonds are single bonds
• Pi (p) bonds are the bonds that follow in a
multiple bond situation
Now you try…
CO
Oxygen
Polyatomic ions
Draw the Lewis Structures for the following
polyatomic ions.
Phosphate
Hydroxide
LS of ions are indicated using [
] and charge
Polyatomic ions
Examples
Warm Up: Draw the Lewis Structures and
indicate the dipoles…
1. CH2F2
2. F2
3. NO31-
Indicate the number of shared and unshared
pairs on each molecule.
.
Resonance Structures
• Some molecules cannot be correctly
identified by a single Lewis structure
• When you can draw two mirror images,
you probably have a resonance structure
– For example: Ozone O3
Visual Concepts
Draw the Resonance Structures for
Selenium Trisulfide
Questions on the LS WS??
How did you do on the polyatomic ions??
Acids to memorize…
Hydrochloric- HCl
Acetic Acid- HC2H3O2
Nitric Acid- HNO3
Sulfuric Acid- H2SO4
Carbonic Acid- H2CO3
Phosphoric Acid- H3PO4
Building Covalent
Molecules Activity
1. Fold paper so that you have 6 squares
on each page.
2. Write the compound formulas in each
box as indicated on the board.
Just a few things from last
semester…
1. Your feedback is very important to me!
a. Students like- CB, notes, activities
b. Mixed reactions- POGILS, Projects
and homework amount.
c. Students didn’t like- IB cut and paste,
worksheet assignment/collection.
2. Performance Assessment / Final.
3. Writing in science.
4. What’s new in the room?
Building Covalent
Molecules Activity
1. Draw the Lewis Structure for each
molecule.
2. Build the molecule using the kits.
3. Determine the Electronegativity of each
atom and determine bond polarity- draw
the dipoles on LS.
4. Draw the 3-D molecule.
5. Determine the molar mass of each
molecule.
Warm UpWrite the names from the formulas…
1. BaSO4
2. MnO4
3. SiO2
4. PO
5. NiPO4
Be sure you are reviewing your Ionic Bonding… all is fair
game for the test next week.
Review Questions?
Test
Warm Up
Determine the formula
1. Calcium hydroxide
2. Vanadium (IV) oxide
3. Phosphorus
tribromide
4. Chlorine
5. Zinc sulfide
Determine the name
1. SrO
2. FePO4
3. PO3
4. HC2H3O2
5. O2
How did you do?
Determine the formula
1. Ca(OH)2
2. VO2
3. PBr3
4. Cl2
5. ZnS
Determine the name
1. Strontium oxide
2. Iron(III) phosphate
3. Phosphorus trioxide
4. Acetic acid
5. Oxygen
Just a few things from last
semester…
1. Your feedback is very important to me!
a. Students like- CB, notes, activities
b. Mixed reactions- POGILS, Projects
and homework amount.
c. Students didn’t like- IB cut and paste,
worksheet assignment/collection.
2. Performance Assessment / Final.
3. Writing in science.
4. What’s new in the room?
Molecular Geometry
VSEPR
Valence Shell, Electron
Pair Repulsion
Theory
VSEPR
• How a molecule “looks” in real space (3D).
• Shape is based upon electron domains
(where electrons are).
Bonds (doubles/triples count as one
domain)
Unshared electron pairs- actually take
more space.
You need to remember…
–Electron domains repel each
other.
–Unshared pairs repel more than
bonding pairs.
–Domains orient themselves as
far away from each other as
possible.
VSEPR
Let’s use balloons to figure out the
molecular geometry of various
compounds!
Here are some video clips that will
show it to you again!
• Development of bond angles
Visual Concepts
• Lone pair geometry
Visual Concepts
Guess the shape!
Polarity- Physical Property
Look at the entire moleculeIf there is an unequal distribution of charge
(dipoles or a bunch of electrons in one spot).
POLAR
If all the bonds are nonpolar or the molecule is
symmetrical (even if it has dipoles), it is
NONPOLAR
Let’s Discuss These!
Let’s revisit the molecules you
built Tuesday…
1. Shape and Bond Angles?
2. Determine the overall polarity.
You can keep these activities to study… be
sure to bring them to hand in on test day!
Is Polarity a Physical or
Chemical Property?
Polarity is important in determining the
reactivity of various molecules.
It helps us understand the interaction
between molecules (intermolecular forces).
It also determines the solubility of the
molecule.
Warm Up – Tues. Honors
Draw the LS and predict the molecular
geometry and bond angles for the following
molecules.
SO22-
SiCI4
BCl3
Intramolecular Forces
We have spent a month talking about
intramolecular forces… the forces between
atoms.
What are they called?
Intermolecular Forces
Forces of Attraction
between Molecules
These forces affect the physical
properties of compounds
Melting and Boiling Points
Volatility
Solubility
What does Volatility mean?
• Volatile Liquid Demo
• Let’s try to figure out why the alcohol this
guy uses is more volatile than water.
Ethanol- C2H6O Draw the LS
Different types of Intermolecular Forces
Dipole-Dipole Force- The negative region of one
molecule is attracted to the positive region of a
different molecule.
HCl, NH3
Induced dipole - When a polar molecule causes a
nonpolar molecule to become polar (temporary).
Visual Concepts
Different types of Intermolecular Forces
• London dispersion - result from the constant
motion of electrons and the creation of
instantaneous dipoles.
• LD Video
Super Important!
• Hydrogen Bonding- When a hydrogen atom
(bonded to a highly electronegative atom)
attracts an unshared pair of electrons from
the atom of a nearby EN atom.
Video 1- Basic
Video 2- A little more deep!
What elements with Hydrogen form H bonds?
Hydrogen Bonding
Get into your small groups and
discuss why ethanol is more
volatile than water.
Metallic Bonding
• This is an extremely strong bond
• Delocalized electrons
Gives metal: luster, malleability, ductility,
conduct electricity and heat
Look at the Polarity of the Molecule
Polar Molecule
• One end negative, one end positive
Dipole
• Molecule that has two poles
• Is created by equal but opposite charges
that are separated by a short distance
Memorize!
• Shapes and angles
– Linear 180o
– Trigonal planar 120o
– Tetrahedral 109.5o
– Trigonal pyramidal 107.5
– Bent 104.5
– Trigonal bipyramidal 90o 120o
– Octahedral 90o
Metals
Share a sea of electrons…
Explains why so many of them are good
conductors of electricity.
Alloys
• Combination of metals
– Bronze: copper and tin
– Brass: zinc and copper
– Coin metal: copper and nickel
– Solder: lead and tin
Substitutional Alloy
• Some of the main metal atoms are
replaced by other metal atoms of similar
size.
• An example is brass where one-third of
the atoms of the host copper are replaced
with zinc atoms.
Interstitial Alloy
• Formed when some of the holes in the
closest packed metal structure are
occupied by small atoms.
• Steel is an interstitial alloy, containing
carbon atoms in the holes of an iron
crystal.
Stainless steel is a mixture of Iron, Chromium and Carbon.
What kind of Alloy would it be?
Questions on the Review???
I will post review answers on-line… feel free
to come see me to answer questions.
Be sure to look over your ionic bonding WS.
Naming Game (Time Permitting)