Covalent Bonds

How to Draw Dot Structures for Covalent Bonds

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

--Atoms share VEs to achieve an Octet.--Circle Test for an Octet--Hydrogen only needs two electrons--Carbon is always the central atom (never hydrogen)--Least electronegative atom goes in the center.--Valence electrons to start = finish.--Look for Symmetry in the drawing.

--Single Bonds --Double Bonds --Triple Bonds--Resonant Structures – Coordinate Bonds

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Hydrogen has 1ve

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Hydrogen has 1ve Chlorine has 7ves

Cl

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Hydrogen has 1ve Chlorine has 7ves

Cl

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Hydrogen has 1ve Chlorine has 7ves

ClThey share their valence electrons

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Hydrogen has 1ve Chlorine has 7ves

ClThey share their valence electrons

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Hydrogen has 1ve Chlorine has 7ves

ClThey share their valence electrons

Circle Test for Octet

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Hydrogen has 1ve Chlorine has 7ves

ClThey share their valence electrons

Circle Test for Octet

Eight Electrons!

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Hydrogen has 1ve Chlorine has 7ves

ClThey share their valence electrons

Circle Test for Octet

Eight Electrons!

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Lewis Diagram for HCl

Cl

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Those two shared electrons represent a single bond and can be written as:

ClH Cl

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Those two shared electrons represent a single bond and can be written as:

ClH ClThe dash represents two

electrons in a single bond.

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Hydrogen has 1ve

H

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Hydrogen has 1ve

HO

Oxygen has 6ves

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Hydrogen has 1ve

HO

Oxygen has 6ves

They Share their valence electrons

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H

Hydrogen has 1ve

HO

Oxygen has 6ves

They Share their valence electrons

Octet Test!

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H HO

The dashes represents two electrons in a single bond.

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

H HO

The dashes represents two electrons in a single bond.

Hydrogen is never the central atom!!!

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Chlorine has 7ves

ClCl

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Chlorine has 7ves

ClCl

Chlorine is Diatomic

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Chlorine has 7ves

ClCl

Chlorine is Diatomic

Chlorine shares its valence electrons

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Chlorine has 7ves

ClCl

Chlorine is Diatomic

Chlorine shares its valence electrons

Octet Test!

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Chlorine has 7ves

ClCl

Chlorine is Diatomic

Chlorine shares its valence electrons

Octet Test!

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Chlorine has 7ves

ClCl

Chlorine is Diatomic

Chlorine shares its valence electrons

Octet Test!

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

ClCl

The dash represents two electrons in a single bond.

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

ClCl

The dash represents two electrons in a single bond.

All the Halogens behave like this!!!!

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

FF

The dash represents two electrons in a single bond.

All the Halogens behave like this!!!!

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

FF

This is why the Halogens are Diatomic!

All the Halogens behave like this!!!!

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

II

This is why the Halogens are Diatomic!

All the Halogens behave like this!!!!

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

BrBr

Bromine is a dark Red Liquid!

All the Halogens behave like this!!!!

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

N

Nitrogen has 5ves

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

N

Nitrogen has 5ves

H H

H

Hydrogen has 1ve

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

N

Nitrogen has 5ves

H HH

Hydrogen has 1ve

Hydrogen and Nitrogen share their valence electrons

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

N

Nitrogen has 5ves

H HH

Hydrogen has 1ve

Hydrogen and Nitrogen share their valence electrons

Octet Test!

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

NH H

H

The dashes represents two electrons in a single bond.

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Carbon has 4ves

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Carbon has 4ves

C

F

F

Covalent Bonds

C

Carbon has 4ves

Fluorine has 7ves

F F

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

F

F

Covalent Bonds

C

Carbon has 4ves

Fluorine has 7ves

F F

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

F

F

Covalent Bonds

C

Carbon has 4ves

Fluorine has 7ves

F F

Octet Test!

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

F

F

Covalent Bonds

C

Carbon has 4ves

Fluorine has 7ves

F F

Octet Test!

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

F

F

Covalent Bonds

C

Carbon has 4ves

Fluorine has 7ves

F F

Octet Test!

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

F

F

Covalent Bonds

C

Carbon has 4ves

Fluorine has 7ves

F F

Octet Test!

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

F

F

Covalent Bonds

C

Carbon has 4ves

Fluorine has 7ves

F F

Octet Test!

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

F

F

Covalent Bonds

CF F

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Assignment:

• H2

• CCl4

• CH4

• NF3

• H2S

The Next three bonds listed involve double and triple bonds and will be covered in the next video.

Draw Covalent Lewis Dot Structures for the molecules on the left.

OO

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Oxygen Has 6ves

OO

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Oxygen Has 6ves

Octet Test???

OO

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Oxygen Has 6ves

Octet Test???

OO

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Oxygen Has 6ves

Octet Test???

Only 7 electrons not 8!

OO

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Oxygen Has 6ves

Octet Test???

Only 7 electrons not 8!

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

We have to use a DOUBLE BOND

O

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

We have to use a DOUBLE BOND

O

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

We have to use a DOUBLE BOND

O

Octet Test

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

We have to use a DOUBLE BOND

O

Octet Test

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

We have to use a DOUBLE BOND

O

Octet Test

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

We have to use a DOUBLE BOND

O

Each dash represents a bond of two shared electrons.

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

We have to use a DOUBLE BOND

O

We usually pair off the unbonded electrons.

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

O

Oxygen has 6 valence electrons.

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

O

Oxygen has 6 valence electrons.

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

O

Oxygen has 6 valence electrons. Carbon has 4

C

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

O

Joining them in a single bond fails the octet test for all three atoms.

C

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

O

Joining them in a single bond fails the octet test for all three atoms.

CSo we have to use a double bond.

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

O CSo we have to use a double bond.

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

O CThey Join and All Atoms pass the Octet Test.

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

O CThey Join and All Atoms pass the Octet Test.

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

O CThey Join and All Atoms pass the Octet Test.

O

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

O CWe Represent these two double bonds like this.

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Nitrogen has 5 Ves.

N N

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

A Single Bond Fails the Octet test.

N N

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

What about a Double Bond?

N N

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

A Double Bond Fails the Octet Test

N N

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Nitrogen Requires a Triple Bond!

N N

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Nitrogen Requires a Triple Bond!

N N

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

This Passes the Octet Test!

N N

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

This Passes the Octet Test!

N N

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

A Triple Bond! Each Dash represents 2 electrons

N N

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Another Way to do this:1) Each Nitrogen has 5 Ves for 10 electrons total2) Start with a Single Bond representing 2 electrons

N N

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Another Way to do this:1) Each Nitrogen has 5 VEs for 10 electrons total2) Start with a Single Bond representing 2 electrons3) Fill in the next 8 electrons …

N N

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Another Way to do this:1) Each Nitrogen has 5 VEs for 10 electrons total2) Start with a Single Bond representing 2 electrons3) Fill in the next 8 electrons …4) Move Electrons into bonds until you have an octet.

N N

Covalent Bonds

• HCl• H20

• Cl2

• NH3

• CF4

• O2

• CO2

• N2

Another Way to do this:1) Each Nitrogen has 5 Ves for 10 electrons total2) Start with a Single Bond representing 2 electrons3) Fill in the next 8 electrons …4) Move Electrons into bonds until you have an octet.

N N

Bond Strength

Think of each bond (dash) as a rubber band holding the atoms together. Two rubber bands is stronger than one but three is stronger than two.

Nitrogen (N2) makes up 78% of our atmosphere and is a really stable and inert molecule

N NOO

FF Weakest

Strongest

[NO3]- Nitrate Ion

Another Way to do this:1) Count the total number of VEs2) Start with a Single Bond representing 2 electrons3) Fill in the next 8 electrons …4) Move Electrons into bonds until you have an octet. [NO3]-

[NO3]- Nitrate Ion

Another Way to do this:1) Count the total number of VEs2) Start with a Single Bond representing 2 electrons3) Fill in the next 8 electrons …4) Move Electrons into bonds until you have an octet. [NO3]-

5VEs18VEs 1VE

24VEs

[NO3]- Nitrate Ion

Another Way to do this:1) Count the total number of VEs2) Start with a Single Bond representing 2 electrons3) Fill in the rest of the electrons…4) Move Electrons into bonds until you have an octet. [NO3]-

5VEs18VEs 1VE

24VEsNO

OO

[NO3]- Nitrate Ion

Another Way to do this:1) Count the total number of VEs2) Start with a Single Bond representing 2 electrons3) Fill in the rest of the electrons…4) Move Electrons into bonds until you have an octet. [NO3]-

5VEs18VEs 1VE

24VEsNO

OO18VEs

Remaining

[NO3]- Nitrate Ion

Another Way to do this:1) Count the total number of VEs2) Start with a Single Bond representing 2 electrons3) Fill in the rest of the electrons…4) Move Electrons into bonds until you have an octet. [NO3]-

5VEs18VEs 1VE

24VEsNO

OO0VEs

Remaining

[NO3]- Nitrate Ion

[NO3]-5VEs

18VEs 1VE

24VEsNO

OO18VEs

Remaining

0VEs Remaining

Oxygen Obeys the Octet!

Another Way to do this:1) Count the total number of VEs2) Start with a Single Bond representing 2 electrons3) Fill in the rest of the electrons…4) Move Electrons into bonds until you have an octet.

[NO3]- Nitrate Ion

[NO3]-5VEs

18VEs 1VE

24VEsNO

OO18VEs

Remaining

0VEs RemainingOxygen Obeys the Octet!

But Nitrogen Does not!

Another Way to do this:1) Count the total number of VEs2) Start with a Single Bond representing 2 electrons3) Fill in the rest of the electrons…4) Move Electrons into bonds until you have an octet.

[NO3]- Nitrate Ion

Another Way to do this:1) Count the total number of VEs2) Start with a Single Bond representing 2 electrons3) Fill in the rest of the electrons…4) Move Electrons into bonds until you have an octet. [NO3]-

5VEs18VEs 1VE

24VEsNO

OO18VEs

Remaining

0VEs RemainingOxygen Obeys the Octet!

But Nitrogen Does not!

Move a Pair from any Oxygen atom and make one double bond!

[NO3]- Nitrate Ion

[NO3]-5VEs

18VEs 1VE

24VEsNO

OO18VEs

Remaining

0VEs RemainingOxygen Obeys the Octet!

But Nitrogen Does not!

Move a Pair from any Oxygen atom and make one double bond!

Another Way to do this:1) Count the total number of VEs2) Start with a Single Bond representing 2 electrons3) Fill in the rest of the electrons…4) Move Electrons into bonds until you have an octet.

[NO3]- Nitrate Ion

[NO3]-5VEs

18VEs 1VE

24VEsNO

OO18VEs

Remaining

0VEs RemainingOxygen Obeys the Octet!

But Nitrogen Does not!

Move a Pair from any Oxygen atom and make one double bond!

Another Way to do this:1) Count the total number of VEs2) Start with a Single Bond representing 2 electrons3) Fill in the rest of the electrons…4) Move Electrons into bonds until you have an octet.

[NO3]- Nitrate Ion

[NO3]-5VEs

18VEs 1VE

24VEsNO

OO18VEs

Remaining

0VEs RemainingOxygen Obeys the Octet!

But Nitrogen Does not!

Move a Pair from any Oxygen atom and make one double bond!

Another Way to do this:1) Count the total number of VEs2) Start with a Single Bond representing 2 electrons3) Fill in the rest of the electrons…4) Move Electrons into bonds until you have an octet.

[NO3]- Nitrate Ion

[NO3]-5VEs

18VEs 1VE

24VEsNO

OO18VEs

Remaining

0VEs RemainingOxygen Obeys the Octet!

But Nitrogen Does not!

Move a Pair from any Oxygen atom and make one double bond!

Another Way to do this:1) Count the total number of VEs2) Start with a Single Bond representing 2 electrons3) Fill in the rest of the electrons…4) Move Electrons into bonds until you have an octet.

[NO3]- Nitrate Ion

[NO3]-5VEs

18VEs 1VE

24VEsNO

OO18VEs

Remaining

0VEs RemainingOxygen Obeys the Octet!

Nitrogen has an Octet!

Move a Pair from any Oxygen atom and make one double bond!

Another Way to do this:1) Count the total number of VEs2) Start with a Single Bond representing 2 electrons3) Fill in the rest of the electrons…4) Move Electrons into bonds until you have an octet.

Assignment:

• O3

• C2H6

• C2H4

• CO• C2H2

• [OH]-

• [NH4]+

•Carbon is always the central atom.•Carbon will bond to itself.•Least electronegative atom in the middle (never H).•Some molecules can have a single and double bond.•All of these obey the octet rule.

Another Way to do this:1) Count the Number of VEs2) Start with a Single Bond representing 2 electrons.3) Fill in the rest of the electrons making octets where possible…4) Move Electrons into bonds until you have an octet.