### Covalent Bond

```Periodic Table Study Guide
How to Draw Lewis
Structures
Lewis Structures
1) Find your element on the periodic table.
2) Determine the number of valence electrons.
3) This is how many electrons you will draw.
Lewis Structures
• Find out which group
in.
• This will tell you the
number of valence
has.
• You will only draw the
valence electrons.
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Groups - Review
Group 1 = 1 electron
Group 2 = 2 electrons
Group 8 = 8 electrons
Except for He, it has 2
electrons
•Each column is
called a “group”
•Each element in a
group has the same
number of electrons
in their outer orbital,
also known as
“shells”.
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•The electrons in the
outer shell are called
“valence electrons”
Location of valence electrons in a
Lewis Dot Structure
• How many total electrons can exist in the
valence shell of H and He?
• How about Li and heavier?
Lewis Dot Structures: Group 2A
Example: Beryllium
1) Write the element symbol.
2) Beryllium is in the 2nd
group, so it has 2 valence
electrons.
3) Starting at the right, draw
2 electrons
4)
(or dots).
What other elements have the
same Lewis Dot Structure?
Why?
Lewis Dot Structures: Group 3A
Example: Boron
check that Boron is in the
3rd group.
3) You should have 3 total
electrons, or dots, drawn
in for Boron.
Lewis Dot Structures: Group 5A
Example: Nitrogen
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
Lewis Structures
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
Lewis Structures
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
Lewis Dot Structures
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
Lewis Structures
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
Lewis Structures
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
Lewis Structures
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
Lewis Dot Structures – Carbon Family
• The elements in the
Carbon family are
unique
• The stability of a an atom in the
carbon family is special.
• Hund’s Rule: An atom
with a half filled shell is
more stable than a
partially filled shell.
• This goes back to the electron
configuration of Carbon.
• 6 total electrons
What you were told to do:
___ ___ ___ ___ ___
1s
2s
2p
What actually happens:
___ ___ ___ ___ ___
1s
2s
2p
Lewis Dot Structure for Carbon Family
Bohr Model of First 20 elements
Complete the Lewis Structure
Worksheet
You should know how to draw
Lewis Structures for the first
20 elements.
Ionic Charge
Atoms that gain or lose
electrons become ions.
• Atoms with low
electronegativity will
lose electrons
– Example: Metals
• Atoms with high
electronegativity will
gain electrons
– Example: Nonmetals
An atom will gain or lose
electrons to become more
stable by having a full
valence shell
– “The octet rule”
• Ionic charge is the net
electric charge that an
atom will have after it
gains/loses electrons to
have a full valence
shell.
Label the following as atoms or ions
Net Charges
What is the net charge of
this atom?
What is the net charge of
these ions?
Ionic Charges of the Representative Elements
Ion Representation
Cations
Anions
• A cation is formed when an
atom gives an electron.
• The cation has more
protons than electrons
• So it has a net positive
charge.
Example:
Sodium atom to Sodium Ion
• An anion is formed when an
atom gains an electron
• The anion has more
electrons than protons
• So it has a net negative
charge.
Example:
Fluorine atom to Fluorine ion
Na [Na]1+
F  [ F ]1−
Fill in the electrons and show the
gained electron with another symbol
Practice: Ionic Charge
Directions
• Draw the Lewis dot
structure
• Show electrons that are
gained or lost
• Determine ionic charge
• Represent as an ion
Examples:
1. Magnesium
2. Phosphorus
Review Questions:
1. Ionic bonds occur between __________ and
__________.
2. When atoms lose electrons they gain a ______
charge.
3. When atoms gain electrons they gain a ______
charge.
4. Atoms that gain or lose electrons are called
________.
5. An ionic bond occurs when atoms ______ or
________ electrons.
Chemical Bonding
Ionic Bonding (form salts)
Covalent Bonding (form molecules)
Ionic Bonds:
Covalent Bonds:
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Naming Ionic Bonds
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Bonding:
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Naming Covalent Bonds:
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Example of 1:1 ratio: Ionic bonds
Salt:
Li + F 
Practice: Ionic Bond formulas
Reaction
K + Cl 
Na + I 
Name
Example of 1:2 ratio: Ionic bonds
Salt
Ca + C 
Practice:
Reaction
Mg + Cl 
Na + S 
Name
Example of 1:3 ratio: Ionic bonds
Salt
Ga + I 
Example of 3:2 Ratio: Ionic Bonds
Name
Covalent Bonding
Covalent Bond
• A bond formed when atoms
share one or more pairs of
electrons
of molecules have covalent
bonds
• Covalent bonds usually form
between two non-metals.
Covalent Bonding
Covalent Bonds:
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Naming Covalent Bonds:
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Now, Read The Bare Essentials of
Polarity comic strip and answer the
questions on the question guide.
Molecular Polarity
Non polar
Polar (dipole molecules)
• When electrons are equally • When electrons are not
attracted to the positive
equally attracted to the
nucleus of each atom the
positive nucleus of each
bond is NON-POLAR
atom the bond is POLAR.
• The molecule will not have • The molecules will have
charged ends (called poles)
oppositely charged ends
(called poles)
• Example: Diatomic
molecules
• Example: Water
Electronegativity
nonpolar covalent, polar covalent,
and ionic bonds
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Polar vs. Nonpolar Molecules
Polar Molecules: Water
Polar molecules: water
The Role of Electronegativity
Remember:
The electronegativity of an atom is its attraction
for another atoms valence electrons.
Brightstorm video:
Covalent Bonding
Diatomic Molecule: Single Bond
(nonpolar)
Covalent Boding
Diatomic Molecules: Double Bond
(Nonpolar)
Covalent Bonding
Diatomic molecule: Triple Bond
(nonpolar)
Circle the Full valence shell of electrons
How many total bonds?
Are these bonds polar or nonpolar?
Indicate the single, double and triple
bonds.
How many total electrons are being
shared?
Lewis dot Structure and Formula
for a Covalent Bond
Circle the valence electrons for each
Representing Elements and Covalent
bonds with Lewis structures
Covalent bonding practice sheets
```