Chemical bonding

1. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 1
Rapid Learning Center
Chemistry :: Biology :: Physics :: Math
Rapid Learning Center Presents …pg
Teach Yourself
High School Chemistryin 24 Hours
1/32
http://www.RapidLearningCenter.com
Chemical Bonding
HS Ch i t R id L i S i
Rapid Learning Center
www.RapidLearningCenter.com/
© Rapid Learning Inc. All rights reserved.
HS Chemistry Rapid Learning Series
Wayne Huang, PhD
Kelly Deters, PhD
Russell Dahl, PhD
Elizabeth James, PhD

2. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 2
Learning Objectives
„4 types of bonds and the
properties associated with
By completing this tutorial you will learn…
properties associated with
those bond types.
„Bond Polarity.
„Valence Bond Theory.
3/32
Concept Map
Chemistry
Studies
Previous content
New content
Ionic
Nonpolar Nonpolar
Clt
Matter
Compounds
One type is
CovalentCovalent
Covalent
Polar
Covalent
Metallic
4 types of bonding
4/32
Valance
Bond
Theory
Most simple bonding theory

3. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 3
Types ofTypes of
Chemical
Bonds
5/32
Definition: Ionic Bond
Ionic Bond– Formed from the electrostatic
attraction between positive and negativelyattraction between positive and negatively
charged ions due to transfer of electrons -
contains both metals and non-metals.
Na
+
Cl
-
6/32
A sodium atom loses an electron to form Na
+
and a chlorine atom gains
that electron to form Cl
-
. An ionic bond is formed between them.

4. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 4
Definition: Covalent Bond
Covalent Bond– Two non-
metals shareelectrons to
form a bond (e g CH)form a bond (e.g. CH
4).
C H
H
H
Sharing 4 pairs of electrons
between 4xH and 1xC atoms
7/32
H
Definition: Polar Covalent Bond
Polar Covalent Bond–
Two non-metals share
electrons unevenly - electrons are closer to one atom than the other.
8/32
CH N

5. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 5
Definition: Metallic Bond
Metallic Bond– Metal
atoms join together and jg
pool their electrons in a large network.
Cu
C
9/32
Cu Cu Cu
Cu
Cu
Four Types of Bonds
Happens
between
Electrons are Characteristics
The different bond types have different properties.
Metals & Non-
metals
Non-metals
Transferred from
one atom to
another to
create ions.
Shared between
2 atoms.
High melting points,
brittle, often dissolve in
water, conduct electricity
when aqueous.
Low melting points, do
not often dissolve in
water, do not conduct
electricity when aqueous.
Ionic
Covalent
10/32
Non-Metals
Metals
Shared unevenly
between 2
atoms.
Shared in a large
pool with all the
atoms.
Medium melting points,
sometimes dissolve in
water, do not conduct
electricity when aqueous.
Soft, conductors of heat
and electricity, do not
dissolve in water.
Polar
Covalent
Metallic

6. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 6
Bond Polarity
11/32
Definition: Polar Bond
Polar Bond– uneven sharing of
electrons due to differences in
electronegativity (i.e. CO
2).electronegativity (i.e. CO
2).
The “pull” an atom has for electrons
it’s sharing in a bond.
Oxygenis more electronegative than Carbon.
The Oxygenwill pull on the electrons harder.
The electrons will move closer to theOxygen
This will leave the Carbon
with a partial positive
charge and Oxygenwith a
12/32
CO O
The electrons will move closer to the Oxygen. partial negative charge.
Note: Due to its symmetry,
CO
2molecule is nonpolar.
Its linear structure does
not have any overall
polarity because the two
polar bonds cancel each
other out.
δ-δ-
δ+

7. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 7
Electronegativity Trends
Increases
In general, electronegativity:
Decreases
13/32
Common Element Electronegativities
Here are 8 common elements & their electronegativities.
Element Electronegativity
H 2.1
C
N
O
F
2.5
3.0
3.5
4.0
14/32
S 2.5
Cl 3.0
Br 2.8
Electronegativity Mnemonic: F > O > N > Cl > Br > S > C > H = FON
(fun) Clown Brings Such CHaos.

8. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 8
Determining a Polar Bond
Look up the electronegativities for the two atoms.
Determine the (absolute value) difference in
electronegativity
1
2
If there is a polar bond, indicate it with an arrow
being drawn toward the more electronegative
electronegativity.
3
Differences of:
0 Æ0.4 = Non-polar covalent bond
0.5 Æ1.4= polar covalent bond
> 1.4 = ionic bond
15/32
element with a cross on the tail.
Example: Determine if each is a polar bond.
C – H C = 2.5
H = 2.1
Difference = 0.4
Non-polar
C – N C = 2.5
N = 3.0
Difference = 0.5
Polar
Definition: Polar Molecules
Polar Molecule– Polar bonds do not cancel
out and the molecule overall has partially
positive and partially negative areaspositive and partially negative areas.
O C O
O
δ-
16/32
H H
Polar bonds, but non-polar molecule Polar bonds, polar molecule
δ+

9. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 9
Polar Molecules and Bond Geometry
δ-
The manner in which we draw a molecule could
affect our determination of polarity.
O
H H
δ
δ+
OH H
17/32
It is important to know the actual 3D arrangement to determine polarity of a molecule.
δ+
Drawing water in this way makes it appear to be a non-polar molecule. Wrong!
However, water actually is shaped
like this, and it is a polar molecule.
Determining Bond Types
18/32

10. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 10
Bond Type Flow Chart
Compound
contains
Metal &
Non-metal
Non-metals
only
Metals
only
Ionic
Bonding
(MgCl
2)
Electronegativity
difference
0-0.4
Electronegativity
difference
0.5–1.4
Metallic
Bonding
(Mg metal)
19/32
0 0.4 0.5 1.4
Covalent
Bonding
(Cl
2)
Polar
Covalent
Bonding
(HCl)
Determining Bond Type Example
Example: Determine the bond type of each:
K–O Metal & non-metalK O Metal & nonmetal
Ionic Bonding
C – O Non-metals
C = 2.5
O = 3.5
Difference = 1.0
Polar Covalent
20/32
C – S Non-metals
C = 2.5
S = 2.5
Difference = 0
Covalent

11. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 11
Valence Bond
Theory
21/32
Definition: Valence Bond Theory
Valence Bond Theory– Bonds are formed
by the orbitals of atoms overlappingby the orbitals of atoms overlapping.
Valence Bond
22/32
HHH H
s-orbital
Valence Bond – A chemical bond formed by sharing valence electrons. A
valence electron, for a main group element, is in the outermost electron
shell. For a transition metal, it can also be in an inner shell.

12. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 12
Sigma & Pi Bonds
23/32
Definition: Sigma Bond - 1
Sigma Bond (σbond) – A bond in which one
pair of electrons is shared. It is formed from
the overlap of2s-orbitals as below (head-to-the overlap of 2 sorbitals as below (headto
head overlap).
H H
24/32
2 hydrogen atoms - each has 1 electron in an
s-orbital.
H H
s-orbital

13. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 13
Definition: Sigma Bond - 2
Sigma Bond (σbond) – A bond in which one
pair of electrons is shared. It is formed from
the overlap of 2 s-orbitals as below (head-to-the overlap of 2 sorbitals as below (headto
head overlap).
HHH H
sigma bond
25/32
HH
2 hydrogen atoms - each have 1 electron in an s-orbital.
As the atoms move together, their s-orbitals overlap
and form a sigma bond.
H H
Definition: Pi Bond - 1
Pi Bond (πbond)–2
nd
or 3
rd
bond between two
atoms. It is formed from parallel p-orbitals
(side-to-side overlap).
O O
p-orbital
26/32
O O
s-orbital
Only the orbitals and
electrons involved in this
bond will be shown.

14. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 14
Definition: Pi Bond - 2
Pi Bond (πbond) –2
nd
or 3
rd
bond between
two atoms. Formed from parallel p-orbitals
(side-to-side overlap).
OOO O
pi bond
27/32
OOO O
sigma bond
Counting Bonds
Each first bond between 2 atoms is a sigma bond.σ
How many sigma and pi bonds are in a molecule?
All 2
nd
and 3
rd
bonds between 2 atoms are pi
bonds.
π
Example: Count the sigma and pi bonds in the following molecule:
HH
28/32
CCCNH
σ
π
12 3 4 5 6
12 3

15. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 15
Diatomic and Polyatomic Compounds
The Valence Bond Theory
works well for diatomic
compounds (H
2,O
2, etc.).compounds (H
2, O
2, etc.).
But what about polyatomic compounds, such as CH
4?
29/32
More complex theories, such as Hybridization
and Molecular Orbital Theory are introduced in
more advanced chemistry courses.
The type of bond can
be determined from the
The type of bond can
be determined from the
Learning Summary
atoms involved, and
each type has common
properties.
atoms involved, and
each type has common
properties.
The Valence BondThe Valence Bond
30/32
The first bond between
two atoms is a σbond,
each addition bond is a
πbond.
The first bond between
two atoms is a σbond,
each addition bond is a
πbond.
The Valence Bond
Theory uses the
overlap of atomic
orbitals for diatomic
compounds.
The Valence Bond
Theory uses the
overlap of atomic
orbitals for diatomic
compounds.

16. High School Chemistry Rapid Learning Series - 15
© Rapid Learning Inc. All rights reserved. :: http://www.RapidLearningCenter.com 16
Congratulations
You have successfully completed
the tutorial
Chemical Bonding
Rapid Learning CenterRapid Learning Center
Rapid Learning Center
Wh t’ N t
Chemistry :: Biology :: Physics :: Math
What’s Next …
Step 1: Concepts – Core Tutorial (Just Completed)
ÆStep 2: Practice – Interactive Problem Drill
Step 3: Recap – Super Review Cheat Sheet
32/32
Go for it!
http://www.RapidLearningCenter.com