Covalent bonding Lewis Diagrams

https://njctl.org/video/?v=z5vVpzFR-aU
Covalent Bonding
& Lewis Diagrams
2021-02-25
www.njctl.org

Table of Contents:
Covalent Bonding
· Introduction to Covalent Compounds
· Covalent Bonding & Lewis Diagrams
· Polyatomic Ions
· Exceptions to the Octet Rule
· Practice Drawing Lewis Diagrams
Click on a topic to go to that section.

Introduction to Covalent
Compounds
Return to Table
of Contents

Chemical Bonds
There are three basic types of chemical bonds:
With Ionic Bonds, the electrostatic attraction between ions
forms ionic compounds.
With Covalent Bonds, valence electrons are shared
between atoms to form either network solids or molecules.
With Metallic Bonds, the valence electrons of many metal
atoms are shared to form a "sea" of electrons within a
metallic solid.
In this unit, we will be studying covalent bonds.

Chemical Bonds
How ionic or covalent a bond is depends on the difference in
electronegativity between the atoms.
The smaller the difference, the more likely electrons are "shared"
and the bond is considered covalent.
The greater the difference, the more likely electrons have been
transferred and the atoms are ionized, resulting in an ionic bond.

Chemical Bonds
Below, we examine the electronegativity difference between fluorine
(F) and some other atoms. The electronegativity of the atoms is
shown below each atomic symbol, including that of F, which is 4.0.
The electronegativity difference between F and each atom is shown
at the bottom of the chart. As the difference decreases, the bond
between F and the other atom becomes increasingly covalent.
Li Be B C N O F
electronegativity 1.0 1.6 2.0 2.5 3.0 3.5 4.0
bond Li-F Be-F B-F C-F N-F O-F F-F
Δ electronegativity 3.0 2.4 2.0 1.5 1.0 0.5 0
Increasingly Covalent Character

Chemical Bonds
While bond character (between ionic and covalent) is a spectrum, we
can make a few simplifications...
· Ionic bonds occur when the difference in electronegativity between
two atoms is 1.7 or greater.
Na ---- F Δ electronegativity = 3
· If the difference of electronegativity is less than 1.7, it is a covalent
bond. Neither atomtakes electrons from the other; they share
electrons. This type of bondingtypically takes place between two
non-metals.
H ---- Cl Δ electronegativity = 1.1

Types of Covalent Compounds
There are two types of compounds created by the covalent
bonding of atoms:
Covalent networks - larger compounds consisting of repeating
elemental or molecular units all covalently bonded together, such
as diamond (Cn) or quartz [(SiO2)n].
Molecules - smaller compounds of one or more elements bonded
together, such as water (H2O) or oxygen gas (O2).

Graphite (C)
Diamond (C)
Covalent Network Compounds
Like ionic and metallic substances, covalent network solids don't
consist of individual molecules.
They form large compounds composed of a continuous "network" of
covalently bonded atoms, represented by formula units.
Below are two covalent network solids formed from carbon (C).

Properties of Covalent Network Compounds
Some properties of covalent network compounds:
· Non-conductive - because they are made of non-metallic
atoms, covalent network solids conduct little or no electricity.
· Hard - because all atoms in the structure are bonded
together, these materials tend to be very hard.
· High melting points - covalent bonds are strong and covalent
networks have many bonds giving them high melting points.

Molecular Compounds
Molecules are different from ionic compounds or network
covalent solids in that they have a specific number of atoms.
Water is made up of two hydrogen atoms and one oxygen atom.
It is not just a fixed ratio to types of atoms. It has a specific
number of each type of atom.
NaCl can have any number of Na and Cl atoms, as long as the
ratio is 1:1.
Each H2O molecule has exactly two hydrogen atoms and one
oxygen atom.

Properties of Molecular Compounds
Atoms within molecules are held together by strong intramolecular
bonds.
Molecules are attracted together by weak intermolecular forces.
As a result, they have different properties than covalent network
compounds. They are:
· Non-conductive: Because they are made of non-metallic atoms,
molecular compounds are excellent insulators.
weak inter-molecular
forces between molecules
· Low melting points - molecules are small and
held together by weak intermolecular forces
(not bonds) that are easy to break.

Naming Binary Molecules
Binary molecules consist of two atoms sharing electrons.
All end in "ide."
Unlike ionic compounds, each element has a prefix that indicates
how many of its atoms are present in the covalent compound.
Examples
NO2 nitrogen dioxide
P2 O5 diphosphorous pentoxide
( penta-oxide-->pentoxide)

Look on your reference sheets for the prefixes - an
example is shown to the right.
The atom with the lower electronegativity is
usually written first.
If there is only one of the first atom, "mono" is left off.
For instance,
CO is carbon monoxide, NOTmonocarbon monoxide.
CO2 is carbon dioxide, NOTmonocarbon dioxide.

Polyatomic Ions were covered in the last unit - they are two
or more atoms covalently bonded together, but they are not
neutral - they have a charge.
Be careful not to confuse them with the neutral covalent
molecules.
Examples
(NO3)- Nitrate is a polyatomic ion with a charge of -1
NO3 Nitrogen Trioxide is a neutral molecule

1 Which pair of atoms will form a covalent bond?
A Li and Ne
B K and Br
C C and O
D Na and Cl
E I need
help
Answer
https://njctl.org/video/?v=UrJnVvbze04

A Li and Ne
B K and Br
C C and O
D Na and Cl
E I need
help
[This object is a pull tab]
Answer
C
https://njctl.org/video/?v=UrJnVvbze04

A Li and Cl
B Na and Cl
C K and Fl
D H and O
E I need
help
Answer
https://njctl.org/video/?v=TycvVmV8t-E

A Li and Cl
B Na and Cl
C K and Fl
D H and O
E I need
help
Answer
D
https://njctl.org/video/?v=TycvVmV8t-E

3 The atoms that would form the MOST covalent bond
would be:
A C - H
B O - H
C Cl - H
D F - H
E I need
help
Answer
https://njctl.org/video/?v=PF5JKZE_83E

3 The atoms that would form the MOST covalent bond
would be:
A C - H
B O - H
C Cl - H
D F - H
E I need
help
Answer
A
https://njctl.org/video/?v=PF5JKZE_83E

4 The bond with the LEAST ionic character below
would be:
A Na - F
B C - F
C Si - H
D Al - O
E I need
help
Answer
https://njctl.org/video/?v=YAqSj7Yblus

4 The bond with the LEAST ionic character below
would be:
A Na - F
B C - F
C Si - H
D Al - O
E I need
help
Answer
C
https://njctl.org/video/?v=YAqSj7Yblus

5 Butter melts on a hot day. What type of compound is it?
A metallic
B ionic
C covalent network
D molecular
E I need help
Answer
https://njctl.org/video/?v=i5ifRTQUvRs

5 Butter melts on a hot day. What type of compound is it?
A metallic
B ionic
C covalent network
D molecular
E I need help
Answer
D
https://njctl.org/video/?v=i5ifRTQUvRs

6 You are given a substance that has a high melting point
and does not conduct electricity, even when you put it in
water. What is it?
A a metal
B an ionic compound
C a covalent network
D a molecule
E I need help
Answer
https://njctl.org/video/?v=kf_C9WW5TZ8

6 You are given a substance that has a high melting point
and does not conduct electricity, even when you put it in
water. What is it?
A a metal
B an ionic compound
C a covalent network
D a molecule
E I need help
Answer
C
https://njctl.org/video/?v=kf_C9WW5TZ8

7 Chlorine monoxide is
A ClO2
B ClO
C OCl
D O2Cl
E I need help
Answer
https://njctl.org/video/?v=3tP0aqWQR_4

7 Chlorine monoxide is
A ClO2
B ClO
C OCl
D O2Cl
E I need help
Answer
B
https://njctl.org/video/?v=3tP0aqWQR_4

8 Dinitrogen tetroxide is
A NO2
B N2O4
C NO3
D N4O2
E I need help
Answer
https://njctl.org/video/?v=Erv00aZl39M

8 Dinitrogen tetroxide is
A NO2
B N2O4
C NO3
D N4O2
E I need help
Answer
B
https://njctl.org/video/?v=Erv00aZl39M

9 H2O is
A Hydrogen monoxide
B Dihydrogen monoxide
C Hydrogen oxide
D Hydrogen dioxide
E I need help
Answer
https://njctl.org/video/?v=eV96TRAN10c

9 H2O is
A Hydrogen monoxide
B Dihydrogen monoxide
C Hydrogen oxide
D Hydrogen dioxide
E I need help
Answer
B
https://njctl.org/video/?v=eV96TRAN10c

10 SO3 is
A sulfate
B sulfur oxide
C sulfur trioxide
D sulfite
E I need help
Answer
https://njctl.org/video/?v=jYpkka4DIKQ

10 SO3 is
A sulfate
B sulfur oxide
C sulfur trioxide
D sulfite
E I need help
Answer
C
https://njctl.org/video/?v=jYpkka4DIKQ

11 P4O10 is
A Phosphorous pentoxide
B Phosphate
C Phosphorous oxide
D Tetraphosphorous decoxide
E I need help
Answer
https://njctl.org/video/?v=AybvvHso2dw

11 P4O10 is
A Phosphorous pentoxide
B Phosphate
C Phosphorous oxide
D Tetraphosphorous decoxide
E I need help
Answer
D
https://njctl.org/video/?v=AybvvHso2dw

12 MgO is
A monomagnesium monoxide
B magnesium monoxide
C magnesium oxide
D monomagnesium oxide
E I need help
Answer
https://njctl.org/video/?v=Xd4qk_-g-fc

12 MgO is
A monomagnesium monoxide
B magnesium monoxide
C magnesium oxide
D monomagnesium oxide
E I need help
Answer
C
https://njctl.org/video/?v=Xd4qk_-g-fc

https://njctl.org/video/?v=ISCeONytrwg
Covalent Bonding
& Lewis Diagrams
Return to Table
of Contents

Atoms tend towards having a full shell electron configuration. For
most atoms, that means having8 valence electrons.
In covalent bonding, an atom will share electrons in an effort to
obtain eight electrons around it (with a few exceptions as shown
below).
The Octet Rule
Exceptions to the Octet Rule
H needs 2e-
Be needs 4e-
B needs 6e-

1 2 13 14 15 16 17 18
Lewis structures are diagrams that show valence electrons as dots.
They are also known as Lewis dot or electron dot diagrams.
Note that no electrons are paired until after the fourth one (with the
exception of Helium).
Lewis Structures

Single Covalent Bond
Two nonmetals will share electrons to complete their outer shell.
Hydrogen (H) and fluorine (F) both need one electron to complete
their outer shell.
Shared pair
of electrons
H H
H H
Forming H2
F F
Forming F2
F
F
Shared pair
of electrons

Lewis Dot Structure
A Lewis dot structure will commonly represent the covalent bonds
by dashes. As in theexamples below, one shared pair of electrons
is represented by onedash.
H
H
Shared pairs
of electrons
H H F F
F
F
Shared pairs
of electrons

A pair of valenceelectrons that is not shared between atoms
is called an unshared pair, also known as alone pair or a
nonbonding pair.
F
F N
H
H
H
Lone pairs
Lone Pairs

There are seven steps to help you draw Lewis Structures:
1. Find the total number of valence electrons in the compound.
2. The central atom is the least electronegative element
(excluding hydrogen because it can only have one bond).
3. Connect the other atoms to it by single bonds.
4. Count each single bond as a pair
(two) of electrons.
Drawing Lewis Structures
continued on the next slide...

5. Add electrons to the outer atoms to
give each one 8 (a full
shell). Remember the exceptions.
6. Do the same for the central atom.
7. Check: Does each atom have a full outer shell?
Have you used up all the valence
electrons? Have you used too
many electrons?
Let's work a couple of examples....

The P atom has 5 valence
electrons.
A Cl atom has 7, and there
are three of them.
The total number of valence
electrons is:
P
Cl Cl
Cl
1. Find the total number of valence
electrons in the compound.
14 15 16 17 18

13 14 15 16 17
18
P has an electronegativity of 2.1 and
has an electronegativity of 3.0
P will be the central atom.
The Cl atoms will surround the P ato
The single bonds are shown as sing
lines.
Cl
P
Cl
Cl
2. The central atom is the least
electronegative element
(excluding hydrogen).
3. Connect the other atoms to it
by single bonds.

4. Count each single bond as a pair
(two) of electrons.
5. Add electrons to the outer atoms to
give each one 8 (a full shell).
Remember the exceptions.
6. Do the same for the central atom.
7. Check: Does each atom have a
full outer shell?
Have you used up all the valence
electrons? Have you used too many
electrons?

The N atom has 5 valence
electrons
and
each of the three H atoms
has 1 so the total number of
valence electrons is,
NH3
5 + 3(1) = 8
1. Find the total number of valence
electrons in the polyatomic ion or
molecule.

2. The central atom is the least
electronegative element
(excluding hydrogen because it
can only have one bond).
3. Connect the other atoms to it
by single bonds.
H can never be the central atom
so N must be the central atom.
The H atoms will surround the N
atom.
The single bonds are shown as
single lines.
H
N H
H
NH3

H
N H
H
Each H already has two
electrons, so that's done. But w
have to add electrons to N to
make 8.
H
N H
H
4. Count each single bond as a
pair (two) electrons. Now add
electrons to the outer atoms to give
each one a full shell (2 in the case
of H).
5. Next, do the same for the central
atom.
6. Check:
Does each atom have a full outer
shell ?
7. Have you used up all the
valence
electrons you started with? Have
you used too many electrons?

13 How many valence electrons does nitrogen have?
A 2
B 3
C 4
D 5
E I need help
Answer
https://njctl.org/video/?v=JfPN6yvE-k4

13 How many valence electrons does nitrogen have?
A 2
B 3
C 4
D 5
E I need help
Answer
D
https://njctl.org/video/?v=JfPN6yvE-k4

14 How many electrons are shared by two atoms to
create a single bond?
A 3
B 2
C 4
D 1
E I need help
Answer
https://njctl.org/video/?v=yqbV2YtF6KU

create a single bond?
A 3
B 2
C 4
D 1
E I need help
Answer
B
https://njctl.org/video/?v=yqbV2YtF6KU

15 How is a covalent bond represented in a Lewis structure?
A a dash
B a dot
C two dots
D both A and C
E I need help
Answer
https://njctl.org/video/?v=qpqRuY3TqqQ

15 How is a covalent bond represented in a Lewis structure?
A a dash
B a dot
C two dots
D both A and C
E I need help
Answer
D
https://njctl.org/video/?v=qpqRuY3TqqQ

16 Which element in H2O is the least electronegative?
A H
B O
C the electronegativities are equal
D H2
E I need help
Answer
https://njctl.org/video/?v=R9P6-toPzEE

16 Which element in H2O is the least electronegative?
A H
B O
C the electronegativities are equal
D H2
E I need help
Answer
A
https://njctl.org/video/?v=R9P6-toPzEE

17 How many total valence electrons does H2O have?
A 18
B 8
C 24
D more information is needed
E I need help
Answer
https://njctl.org/video/?v=N6ocPuZrAbY

17 How many total valence electrons does H2O have?
A 18
B 8
C 24
D more information is needed
E I need help
Answer
B
https://njctl.org/video/?v=N6ocPuZrAbY

https://njctl.org/video/?v=ofw7dNVHm50
Practice Drawing
Lewis Diagrams
Return to Table
of Contents

I
Practice: I2
Elements Bonds & Electrons
Drag and drop the required elements, bonds and
electrons from above into the workspace below or
draw them in your notes.
Check your answer on the next page.

I
Practice: I2
I I

I
Cl
Practice: Cl2
Drag and drop the required elements, bonds and electrons from
above into the workspace below or draw them in your notes.

I
Practice: Cl2
Cl Cl
Cl

I
Cl H C
Practice: CH4

I
Practice: CH4
C
H
H
H
H
Cl H C

18
The Lewis structure for nitrogen is N
A True
B False
C I need help
Answer
https://njctl.org/video/?v=Oa0FPayHqDs

18
The Lewis structure for nitrogen is N
A True
B False
C I need help
Answer
True
https://njctl.org/video/?v=Oa0FPayHqDs

19 Which of the following need fewer than 8 valence
electrons to be stable?
A Boron and Beryllium
B Boron and Helium
C Boron, Beryllium, and Hydrogen
D Boron, Beryllium, Hydrogen and Oxygen
E I need help
Answer
https://njctl.org/video/?v=YE_CKH0rbC4

19 Which of the following need fewer than 8 valence
electrons to be stable?
A Boron and Beryllium
B Boron and Helium
C Boron, Beryllium, and Hydrogen
D Boron, Beryllium, Hydrogen and Oxygen
E I need help
Answer
C
https://njctl.org/video/?v=YE_CKH0rbC4

20 Which of the following is the correct Lewis Structure for
H2O?
H O H
H H O
H H
O
H H
O
A
B
C
D
E I need help
Answer
https://njctl.org/video/?v=hZ2Y4durWUk

20 Which of the following is the correct Lewis Structure for
H2O?
H O H
H H O
H H
O
H H
O
A
B
C
D
E I need help
Answer
D
https://njctl.org/video/?v=hZ2Y4durWUk

21 Which of the following is the correct Lewis Structure
for PH3?
H P H H
H P H
H
H H
P
H
H P H
A
B
C
D
E I need help
Answer
https://njctl.org/video/?v=oEeXrvlCK1Q

21 Which of the following is the correct Lewis Structure
for PH3?
H P H H
H P H
H
H H
P
H
H P H
A
B
C
D
E I need help
Answer
B
https://njctl.org/video/?v=oEeXrvlCK1Q

A
B
C
D
22
H H H H H H C C
C C H
H
H
H
H H
Which of the following is the correct Lewis Structurefor
C2H6?
C C H
H
H H H
H
C C H
H
H H H
H
Answer
https://njctl.org/video/?v=5XD-x96UBmU

A
B
C
D
22
H H H H H H C C
C C H
H
H
H
H H
Which of the following is the correct Lewis Structurefor
C2H6?
C C H
H
H H H
H
C C H
H
H H H
H
Answer
B
https://njctl.org/video/?v=5XD-x96UBmU

https://njctl.org/video/?v=gejTVeHyuU4
Double & Triple Bonds
Return to Table
of Contents

If you run out of electrons before the central atom has
an octet……form multiple bonds until it does.
Not Enough Electrons?

Double and Triple Covalent Bonds
Atoms form double or triple covalent bonds if they can attain
a full energy shell by sharing two pairs or three pairs of electrons.
A bond that involves two shared pairs of electrons is a
double covalent bond.
A bond formed by sharing three pairs of electrons is a triple
covalent bond.
Click here to view an
interactive activity on
covalent bonding

Covalent Bond Length
Adding additional bonds between the same elements decreases the
length of the bonds.
Triple bonds are shorter than double bonds, which are shorter than
single bonds.

Covalent Bond Energy
It requires more energy to break double and triple bonds
compared to single bonds.
Triple bonds are the strongest of the three.
Bond Type Bond Energy
C C
C C
C C
348 kJ
614 kJ
839 kJ
Bond Type Bond Energy
N N 163 kJ
418 kJ
941 kJ
N N
N N

Carbon Dioxide, CO 2
1. Determine the # of valence electrons.
1 (4) + 2 (6) = 16 e-
This leaves 12 electrons, 6 pairs
3. Place lone pairs on oxygen atoms to give each 8.
Double Covalent Bonds
O C O
O C O
2. Form Single Bonds

O C O
O C O
O C O
Carbon Dioxide, CO2
4. Check: We had 16 electrons to
work with; how many have we used?
5. Carbon does not have enough
electrons to complete it's shell. We
must form DOUBLE BONDS between
C and O.
Instead of sharing only 1 pair, a
double bond shares 2 pairs. So one
pair is taken away from each atom
and replaced with another bond.

I
Practice: O2
Cl H C O

I
Practice: O2
Cl H C O
O O

I
Practice N2
Cl H C O N

I
Practice N2
Cl H C O N
N N

I
Practice: CO
Cl H C O N

I
Practice: CO
Cl H C O N
C O
Note: the 3rd bond in this structure is know as a coordinate
covalent bond because both electrons are contributed from a single
atom, the oxygen.

Diatomic Elements
Seven elements in the periodic table are always diatomic.
In their elemental state, they are always seen as two atoms
covalently bonded together.
H2 , O2, N2 , Cl2 , Br2 , I2 , F2
H
O
N
Cl
Br
I
F
Which of these
diatomic
elements
contains a
double bond?
Which contain
triple bonds?

Diatomic Elements
Seven elements in the periodic table are always diatomic.
In their elemental state, they are always seen as two atoms
covalently bonded together.
H2 , O2, N2 , Cl2 , Br2 , I2 , F2
H
O
N
Cl
Br
I
F
N2 is triple bonded.
O2 is double bonded.
H2, F2, Cl2, Br2 & I2
have single bonds.

create a double bond?
A 4
B 2
C 8
D 6
E I need help
Answer
https://njctl.org/video/?v=iU_EKfF_RLI

create a double bond?
A 4
B 2
C 8
D 6
E I need help
Answer
A
https://njctl.org/video/?v=iU_EKfF_RLI

24 How many electrons are shared by two atoms
to create a triple bond?
A 4
B 2
C 8
D 6
E I need help
Answer
https://njctl.org/video/?v=qtqfjCwcFoU

24 How many electrons are shared by two atoms
to create a triple bond?
A 4
B 2
C 8
D 6
E I need help
Answer
D
https://njctl.org/video/?v=qtqfjCwcFoU

25 As the number of bonds between a pair of atoms
increases, the distance between the atoms:
A increases
B decreases
C remains unchanged
D varies, depending on the atoms
E I need help
Answer
https://njctl.org/video/?v=d07lxBdPT08

increases, the distance between the atoms:
A increases
B decreases
C remains unchanged
E I need help
Answer
B
https://njctl.org/video/?v=d07lxBdPT08

increases, the strength of the bond between the
atoms:
A increases
B decreases
C remains unchanged
E I need help
Answer
https://njctl.org/video/?v=EZKmLTRzbwE

increases, the strength of the bond between the
atoms:
A increases
B decreases
C remains unchanged
E I need help
Answer
A
https://njctl.org/video/?v=EZKmLTRzbwE

increases, the energy of the bond between the
atoms:
A increases
B decreases
C remains unchanged
E I need help
Answer
https://njctl.org/video/?v=VxU1hKb7TgY

increases, the energy of the bond between the
atoms:
A increases
B decreases
C remains unchanged
E I need help
Answer
A
https://njctl.org/video/?v=VxU1hKb7TgY

28 Which of the following molecules has a double bond?
A Br2
B BH3
C I2
D O2
E I need help
Answer
https://njctl.org/video/?v=NVpo2Cx2EBA

28 Which of the following molecules has a double bond?
A Br2
B BH3
C I2
D O2
E I need help
Answer
D
https://njctl.org/video/?v=NVpo2Cx2EBA

29 Which of the following elements is not diatomic in its
elemental state?
A Br2
B S2
C I2
D O2
E I need help
Answer
https://njctl.org/video/?v=Nt_UDFMPU8A

29 Which of the following elements is not diatomic in its
elemental state?
A Br2
B S2
C I2
D O2
E I need help
Answer
B
https://njctl.org/video/?v=Nt_UDFMPU8A

30 Which of the following molecules has a triple bond?
A NaCl
B NH3
C N2
D SO2
E I need help
Answer
https://njctl.org/video/?v=d4_DDTajh94

30 Which of the following molecules has a triple bond?
A NaCl
B NH3
C N2
D SO2
E I need help
Answer
C
https://njctl.org/video/?v=d4_DDTajh94

31 Using Lewis structure drawings, determine which
molecule below would have the shortest bond length
between atoms.
A O2
B F2
C Cl2
D CO
E I need help
Answer
https://njctl.org/video/?v=MvFC44e3y84

31 Using Lewis structure drawings, determine which
molecule below would have the shortest bond length
between atoms.
A O2
B F2
C Cl2
D CO
E I need help
Answer
D
https://njctl.org/video/?v=MvFC44e3y84

32 Which of the following shows the correct Lewis structure
for O3?
A
B
C
D Both A & C
O
O O
O
O
O
O O O
E I need help
Answer
https://njctl.org/video/?v=N9CtamcQvB8

32 Which of the following shows the correct Lewis structure
for O3?
A
B
C
D Both A & C
O
O O
O
O
O
O O O
E I need help
Answer
D
https://njctl.org/video/?v=N9CtamcQvB8

https://njctl.org/video/?v=kEwqwYlxSkA
Polyatomic Ions
Return to Table
of Contents

Recall that a polyatomic ion is a group of atoms bonded together
that have a charge and acts like a single unit or ion.
This atoms in these ions are covalently bonded.
For example:
Sulfate = (SO4)2-
Nitrate = (NO3)-
Carbonate = (CO3)2-
Polyatomic Ions

Lewis Structures for Ions
If you are drawing the Lewis Structure for an
ION...
A negative ion hasextra electrons; add the charge of the ion to your
valence electron count.
ClO2
- has 1(7) + 2(6)+ 1 = 20 electrons
A positive ion is missing electrons , subtract the charge of the ion to
your valence electron count.
NH4
+ has 1(5) + 4(1)-1 = 8 electrons

Lewis Structures for Ions
Drawing the Lewis structure of ions follows the same steps as
molecules. Except f
or an ion, brackets [ ] are added around the
Lewis structure and the charge is indicated.
N H
H
H
H
+
Ammonium Ion
https://njctl.org/video/?v=PiZjj4hQAVc

I
Practice:H3O+
Cl H C O N S
For Ions
+ -

I
Practice:H3O+
Cl H C O N S
For Ions
+ -
+

I
Practice NO3
-
Cl H C O N S
For Ions
+ -

I
Practice NO3
-
Cl H C O N S
For Ions
+ -
Any of these are acceptable.

33 How many valence electrons does CO3
2-
have?
A 22
B 18
C 20
D 24
E I need help
Answer
https://njctl.org/video/?v=5CiqerILiuo

33 How many valence electrons does CO3
2-
have?
A 22
B 18
C 20
D 24
E I need help
Answer
D
https://njctl.org/video/?v=5CiqerILiuo

34 How many valence electrons does H3O+ have?
A 7
B 8
C 9
D 10
E I need help
Answer
https://njctl.org/video/?v=NScFSR31Pzc

34 How many valence electrons does H3O+ have?
A 7
B 8
C 9
D 10
E I need help
Answer
B
https://njctl.org/video/?v=NScFSR31Pzc

35 Which of the following is the correct Lewis structure for
the ammonium ion?
A
B
C
D
N H
H
H
H
+
N H
H
H
H
N H
H H
H
N H
H
H
E I need help
Answer
https://njctl.org/video/?v=PY5PYeUdvzs

the ammonium ion?
A
B
C
D
N H
H
H
H
+
N H
H
H
H
N H
H H
H
N H
H
H
E I need help
Answer
B
https://njctl.org/video/?v=PY5PYeUdvzs

the cyanide ion?
A
B
C
D
C N
-
C N
-
C N
-
All of these are correct
E I need help
Answer
https://njctl.org/video/?v=KnuuRLS8lk8

the cyanide ion?
A
B
C
D
C N
-
C N
-
C N
-
All of these are correct
E I need help
Answer
A
https://njctl.org/video/?v=KnuuRLS8lk8

https://njctl.org/video/?v=HU9xZf6tarw
Return to Table
of Contents

There are three types of ions or molecules that do not follow
the octet rule:
#1 Ions or molecules with less than an octet
#2 Ions or molecules with an odd number of electrons
#3 Ions or molecules with more than eight valence electrons
(an expanded octet)

Fewer Than Eight Electrons
As previously mentioned, Hydrogen, Beryllium, and
Boron do not follow the octet rule.
Hydrogen - only requires 2 electrons to complete its
1s orbital.
Beryllium - this metal is shown to form molecular
compounds, rather than ionic compounds
as expected; only needs 4 electrons to be stable.
Boron - only needs 6 electrons to be stable. B
Be
H

Though relatively rare and usually quite unstable and reactive,
there are ions and molecules with an odd number of electrons.
NO is an example:
Odd Number of Electrons

Some molecules form with more than 8
electrons around the central atom. This is
called an expanded octet.
PCl5 , for example, exists when
phosphorus has 10 electrons around it.
Atoms on the third energy level or higher
are allowed to expand their octet to 10 or
12 electrons.
Expanded Octet

I
Practice: SF6
Cl H C O N S
F For Ions
+ -

https://people.uwplatt.edu/~sundin/images/lewsf6.gif
I
Practice: SF6
Cl H C O N S
F For Ions
+ -

I
Practice:XeF4
Cl H C O N S
F Xe For Ions
+ -

I
Practice:BF3
Cl H C O N S
F Xe B For Ions
+ -

iodine trichloride?
A
B
C
D
I Cl
Cl
Cl
I Cl
Cl
Cl
I Cl
Cl
Cl
I Cl
Cl
Cl
E I need help
Answer
https://njctl.org/video/?v=7emWqIP0KqM

iodine trichloride?
A
B
C
D
I Cl
Cl
Cl
I Cl
Cl
Cl
I Cl
Cl
Cl
I Cl
Cl
Cl
E I need help
Answer
A
https://njctl.org/video/?v=7emWqIP0KqM

38 The correct lewis structure for BeCl 2 is:
Cl - Be - Cl
A True
B False
C I need help
Answer
https://njctl.org/video/?v=IjRZF6Kjke4

38 The correct lewis structure for BeCl 2 is:
Cl - Be - Cl
A True
B False
C I need help
Answer
False
https://njctl.org/video/?v=IjRZF6Kjke4

39 Elements in the first two rows of the periodic table
cannot have expanded octets because their atoms do
not have enough space.
A True
B False
C I need help
Answer
https://njctl.org/video/?v=9p7g669Hfaw

39 Elements in the first two rows of the periodic table
cannot have expanded octets because their atoms do
not have enough space.
A True
B False
C I need help
Answer
True
https://njctl.org/video/?v=9p7g669Hfaw

40 Which compound below contains an atom that is
surrounded by more than an octet of electrons?
A PF5
B CH4
C NBr3
D OF2
E I need help
Answer
https://njctl.org/video/?v=ctnznW54J-Y

40 Which compound below contains an atom that is
surrounded by more than an octet of electrons?
A PF5
B CH4
C NBr3
D OF2
E I need help
Answer
A
https://njctl.org/video/?v=ctnznW54J-Y

Covalent bonding Lewis Diagrams

Covalent bonding Lewis Diagrams

More Related Content

Similar to Covalent bonding Lewis Diagrams

Recently uploaded

Covalent bonding Lewis Diagrams