Covalent Bonding Lesson

ELEMENT

• There are more than 100

different elements found on
Earth.

• An element is a type of atom

with the same number of
protons.

• The term element is also used

to describe a substance that is
made of the same type of
atom.

• Elements are pure chemical

substances.

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Chemistry

1
H

Hydrogen

1.00794

8
O

Oxygen

28
Ni

Nickel

58.6934

COMPOUND

• Elements can chemically combine to form new, pure chemical

substances.

• A chemical substance that is made of two or more different

elements that chemically combine together is called a
compound.

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Chemistry

Element A

Element B

Compound

Categorize

Options (14)

Na

Zn

H2

O2

Cl2

Mg

P

Al

NaCl

KBr

MgS

CaS

H2SO4

Al(NO)3

Organize these options into the right categories

Elements

Compounds

CHEMICAL BONDS

• Elements chemically combine by forming chemical bonds.
• A chemical bond is an attraction between atoms.

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Chemistry

Chemical Bond

• When atoms connect to each other by a

chemical bond, a molecule is formed.

• A molecule is a chemically pure substance

that is made of two or more atoms bonded
together. The atoms can be of the same or
of different elements.

• A compound is a molecule that is made of

two or more different elements.

• All compounds are molecules, but not all

molecules are compounds.

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Chemistry

A molecule, but NOT a

compound

A molecule AND a

compound

CHEMICAL BONDS

Multiple Choice

What is a diatomic molecule?

• When the atoms are of the same element.

• When the atoms are of different elements.

• The smallest particle of a compound that maintains the compound's properties.

• When a metal joins with a nonmetal.

Multiple Choice

What's an example of a diatomic molecule?

• H + Cl

• H + H

• Na + Cl

VALENCE ELECTRONS

• Atoms form chemical bonds through

the interaction of their electrons.
Specifically, the electrons in the
outermost shell.

• The electrons in the outermost shell

are called valence electrons. For this
reason, the outermost shell is also
called the valence shell.

• Atoms form bonds so to attain a full

valence shell. Atoms will transfer or
share electrons in order to do this.

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Chemistry

Valence electrons

Multiple Choice

Electrons in the last shell are called

• Valence electrons

• Hard electrons

• Outside electrons

• Best electrons

VALENCE ELECTRONS

• Some elements have a full valence shell.

These elements are called Noble Gases.

• Noble gases are found in Group 18 on the

periodic table. They are:
– Helium
– Neon
– Argon
– Krypton
– Xenon
– Radon

• Noble gases are inert. They do not readily

form bonds because they have a full
valence shell.

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Chemistry

Multiple Choice

How many valence electrons does Helium (He) have?

• 1

• 2

• 4

• 8

• An atom with 1 or 2 valence

electrons will lose electrons. In
doing so, it develops a full outer
shell because its full inner shell
becomes the outer shell. Losing
electrons make the atom
positively charged.

• An atom with nearly a full outer

shell will gain electrons. In
doing so, its outer shell
becomes full. Gaining electrons
makes the atom negatively
charged.

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Chemistry

VALENCE ELECTRONS

• With most atoms, a full valence shell contains 8 electrons.
• Some atoms will lose electrons and have a full valence shell

that contains only 2 electrons. Remember... the first electron
shell can only hold 2 electrons.

• Examples: Lithium and Beryllium

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Chemistry

VALENCE ELECTRONS

• Hydrogen is different from other elements. It has one electron

shell and one valence electron.

• If hydrogen gained one electron, it would have a full outer

shell. However, it’s easier (and requires less energy) for
hydrogen to lose its only electron. In doing so, hydrogen has
no electrons – it is merely an atomic nucleus.

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Chemistry

Sometimes we call a
hydrogen ion (H+) a
proton because the

only subatomic

particle in a H+ ion IS

a proton.

VALENCE ELECTRONS

Multiple Choice

How many valence electrons?

• 2

• 3

• 4

• 5

Multiple Choice

What is a valence electron?

• an electron that is found in the outermost shell of an atom. 
• an electron found in the innermost shell of an atom.
• an electron found in the middle shell.

Multiple Choice

How many valence electrons does Bromine (Br) have?

• 5

• 6

• 7

• 8

Multiple Choice

How many valence electrons does Lithium (Li) have?

• 8

• 1

• 5

• 2

Multiple Choice

Electrons are arranged around the nucleus in regions called

• Energy floors

• Energy shelves

• Energy levels

• Energy clouds

Multiple Choice

How many electrons are in Group 15?

• 15

• 5

• 10

• 37

LEWIS DOT DIAGRAMS

• When studying chemical bonding, scientists like to draw

diagrams to show the valence electrons of an element. This
helps them understand how elements bond.

• A Lewis Dot Diagram is a diagram that shows the valence

electrons of an element.

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Chemistry

To draw a Lewis Dot Diagram:
•Determine the number of valence electrons of the element.

•Write the symbol for the element.

•Draw a dot to the right of the symbol to represent the 1st valence e-.

•Draw a dot below the symbol to represent the 2nd valence e-.

•Draw a dot to the left of the symbol to represent the 3rd valence e-.

•Draw a dot above the symbol to represent the 4th valence e-.

•Repeat the pattern (right, below, left, above) to show all the valence
electrons for the element.

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Chemistry

LEWIS DOT DIAGRAMS

LEWIS DOT DIAGRAMS

• Draw a Lewis dot diagram for Carbon (4 valence electrons).

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Chemistry

Hotspot

Click on the dots to fill in the valence electrons for Carbon. Make sure to follow the electron numbers

LEWIS DOT DIAGRAMS

• Draw a Lewis dot diagram for Oxygen (6 valence electrons).

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Chemistry

Hotspot

Click on the hotspots to fill in the valence electrons for Oxygen. Make sure to follow the electron numbers

CHEMICAL BONDS

• There are two main types of strong, chemical bonds:

– Ionic Bonds
– Covalent Bonds

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Chemistry

COVALENT BOND

• In a covalent bond, atoms share electrons.
• Some atoms do not have a full outer shell. However, they do

not easily lose or gain electrons.

• These atoms will share electrons with other atoms in order to

achieve a full outer shell.

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Chemistry

• Covalent bonds most often occur between nonmetals.

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Chemistry

COVALENT BOND

Categorize

Options (12)

Calcium (Ca)

Magnesium (Mg)

Aluminum (Al)

Iron (Fe)

Copper (Cu)

Potassium (K)

Oxygen (O)

Sulfur (S)

Chlorine (Cl)

Carbon (C)

Bromine (Br)

Iodine (I)

Organize these options into the right categories

Metals

Nonmetals

Multiple Choice

What two types of atoms make a covalent bond?

• 2 Nonmetals
• 1 Nonmetal & 1 Metal
• 2 Metals
• 2 Noble Gases

• Example: Hydrogen and Oxygen
• Hydrogen has 1 valence electron.

Oxygen has 6 valence electrons.

• Oxygen will form 2 covalent bonds

with 2 different hydrogen atoms. In
each bond, oxygen shares 1 electron
with hydrogen and hydrogen shares 1
electron with oxygen.

• By bonding this way, oxygen and

hydrogen both have full outer shells.

• You can rearrange dots on a Lewis Dot

diagram to draw covalent bonds.

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Chemistry

O and H

share electrons

H has 1

valence e-

O has 6

valence e-

COVALENT BOND

We use Lewis dot diagrams to draw
covalent bonds as well. To do this:
1.

Draw the Lewis Dot diagram for the
atoms.

2.

If needed, rearrange the dots around
each diagram to more easily show how
electrons will be shared.

3.

Draw a single line “−” to symbolize a
covalent bond. This line connects the
atoms together and represents a pair of
electrons – one from each atom.

4.

The unbonded valence electrons are left
as dots around each atom and symbolize
unshared electrons.

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Chemistry

COVALENT BOND

• Most often, atoms share one

electron with each other. This is
called a single covalent bond.

• A single covalent bond is

represented with a “−.”

• In the diagram to the right,

carbon forms 4 single covalent
bonds with 4 separate hydrogen
atoms.

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Chemistry

COVALENT BOND

• Atoms can share two electrons

with each other. This is called a
double covalent bond.

• A double covalent bond is

represented with a “=.”

• In the double covalent bond

shown to the right, carbon
shares two electrons with
oxygen and oxygen shares two
electrons with carbon. By
sharing 2 pairs of electrons,
each atom attains a full valence
shell.

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Chemistry

Each atom
shares 2 e-

COVALENT BOND

• Atoms can share three electrons

with each other. This is called a
triple covalent bond.

• A triple covalent bond is

represented with a “ .”

• In the triple covalent bond shown

to the right, two nitrogen atoms
share 3 electrons. Each nitrogen
atom shares 3 electrons with the
other. By sharing this many
electrons, each atom attains a full
valence shell.

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Chemistry

−−−

Each atom
shares 3 e-

COVALENT BOND

• Covalent bonds can occur between atoms of the same

element.

• A diatomic molecule is a molecule made of two atoms of the

same element bonded together.

• There are 7 elements that form diatomic molecules:

• The atoms of these elements are always found bonded

together as pairs.

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Chemistry

– Hydrogen – Fluorine
– Oxygen – Iodine
– Nitrogen – Bromine
– Chlorine

COVALENT BOND

​See next slide to fill out 7 diatomic elements

LIST THE 7 NATURALLY OCCURING DIATOMIC ELEMENTS

• ​Hydrogen Gas (H₂)

• Nitrogen Gas (N₂)

• Oxygen Gas (O₂)

• Fluorine Gas (F₂)

• Chlorine Gas (Cl₂)

• Bromine (Br₂)

• Iodine (I₂)

Categorize

Options (14)

H₂

N₂

O₂

F₂

Cl₂

Br₂

I₂

He₂

Ne₂

B₂

Be₂

C₂

Fe₂

In₂

Organize these options into the right categories

Naturally Occuring Diatomic Element

NOT a Naturally Occuring Diatomic Elemen

Practice Time. Use what you just learned to answer the following questions

Multiple Choice

What is it called if there are three-pairs of electrons being shared?

• Triple bond
• Bond length
• Tribond
• Chocolate Mousse

Multiple Choice

What is a diatomic element?

• a metal bonded with a nonmetal
• 2 or more nonmetals bonded together
• 2 or more metals bonded together
• 2 atoms of the same element bonded together

Multiple Choice

How many electrons are shared in a double bond?

• 2
• 4
• 6
• 8

Multiple Choice

According to the octet rule most elements need _______ valence electrons.

• 2
• 8
• 6
• 18

Multiple Choice

Covalent compounds

• Share electrons
• transfer electrons
• contain a sea of electrons
• conduct electricity

Multiple Choice

Which is the correct molecular structure for carbon dioxide?

Multiple Choice

How many electrons does each line indicate are shared?

• 1
• 2
• 3
• 4

Multiple Choice

Which of the following is a Diatomic Molecule 

• K₂
• C₂
• S₂
• N₂

Multiple Choice

Which of the following describes covalent bonds?

• Bonds form because of opposite charges
• Bonds form to fill outer electron shells
• Electrons are transferred between atoms
• Covalent bonds are magical

Multiple Choice

Other than Hydrogen, how many electrons do atoms need in order to have a full outer shell?

• 2

• 4

• 6

• 8