Introduction to Bonding

Bonding, Naming

and Formulas

Objective 1: WHAT IS A
CHEMICAL BOND?

► A chemical bond is an attraction that

holds atoms together.

► Why do elements bond? In nature, the

lowest energy arrangement is favored.
When chemical bonds form, energy is
released, resulting in a lower energy arrangement.

Objective 2:
ELECTRONEGATIVITY AND ITS
TREND

► Electronegativity is the tendency of an

atom in a molecule to attract shared
electrons to itself.

► Electronegativity generally increases

going from left to right across a period
and decreases going down a group.

Electronegativity Trend

►

Increases across the period and decreases down the group.

Multiple Choice

Which has the greater EN: 
Cl or Al?

• Cl
• Al

Multiple Choice

Electronegativity is...

• how good an atom is at attracting electrons
• the ability of an atom to lose electrons
• the energy required to remove an electron from a specific atom
• how easy it is to make friends. 

Objective 3: TYPES OF
BONDS

► Ionic bonding- results from the electrical

attractions between positive ions
(cations) from metals and negative ions
(anions) from nonmetals. Ionic bonding
forms a neutral arrangement of atoms
called an ionic compound.

► Covalent bonding- results from the sharing of electron

pairs between two atoms. These two atoms are usually
both nonmetals. Covalent bonding forms a neutral
arrangement of called a molecule.

► Metallic bonding - Metallic bonds are found only in

metals. Freely moving valence electrons are attracted
to the positive metal ions.

Types of Bonds

Ionic

Covalent

Metallic

Bond Formation

e- are

transferred from

metal to
nonmetal

e- are shared
between two

nonmetals

e- are

delocalized
among metal

atoms

Type of Structure

Crystal Lattice

True Molecules

“Electron Sea”

Physical State

Solid

Liquid or Gas

Solid

Melting Point

High

Low

Very High

Soluble in Water

Yes

Usually Not

No

Electrical Conductivity

Yes (solution or

liquid)

No

Yes (any form)

Other Properties

Odorous

Malleable,

Ductile, Lustrous

Types of Bonds – Ionic
Bonding

Diatomic
Molecule

Covalent Bonding - True Molecules

Types of Bonds

Diatomic
Molecule

Metallic Bonding - “Electron Sea”

RETURN

Types of Bonds

Multiple Choice

Sea of electrons

• Metallic Bonding

• Ionic Bonding

• Covalent Bonding

Multiple Choice

Shares electrons in order to fill an energy level

• Metallic bond

• Ionic bond

• Covalent Bond

Multiple Choice

Attraction of oppositely charged ions

• metallic

• covalent

• Ionic

Multiple Choice

Generally occurs between metal and nonmetal

• Metallic

• Ionic

• Covalent

Multiple Choice

Forms large crystals with an ordered arrangement of oppositely charged ions

• Metallic

• Ionic

• Covalent

Objective 4: RELATE
ELECTRONEGATIVITY DIFFERENCES
TO BOND POLARITY.

►

The greater the EN difference in a compound, the more
polar the bond.

►

Bonding electrons will be unequally shared if there is
an electronegativity difference. The atom with the
higher electronegativity value will have a stronger
attraction for the shared electrons. If the EN difference
is greater than or equal to 1.7, the bond is considered
an ionic bond.

Bond Polarity

Examples:

►

Cl2

►

HCl

►

NaCl

3.0-3.0=0.0
Nonpolar

3.0-2.1=0.9
Polar

3.0-0.9=2.1
Ionic

Bond Polarity

► Most bonds are a

blend of ionic and
covalent
characteristics.

► Difference in

electronegativity
determines bond
type.

Multiple Choice

What is the electronegativity of Chlorine gas(Cl₂)

• 0

• 1

• 2

Multiple Choice

What is the bond polarity if the electronegativity difference ranges from 0 to 0.3?

• Nonpolar Covalent

• Polar Covalent

• Ionic

Objective 5: IONIC BONDING

►

Electronegativity difference is greater than or equal to
1.7

►Involves the transfer of electrons to make a full octet

►Example: NaCl

►NaCl: ____ - _____ = ________

► Ionic compound- composed of positive cations

and negative anions that are combined so that
the net charge is zero.

► Formula unit- simplest collection of atoms from

which an ionic compound’s formula can be
established. Example: the formula unit for sodium
chloride is NaCl; a ratio of one Na+ ion to one Cl-
ion.

Ionic Bonding - Crystal Lattice

Types of Bonds

C. Ionic compounds combine in an orderly
arrangement called a crystal lattice.

Sodium chloride crystal lattice

D. Lewis structures for ionic compounds:

►

Draw Lewis structure diagrams showing the formation of NaCl.

Lewis Structures

►

Ionic – show transfer of e-

Lewis Structures

►

Ionic – show transfer of e-

►

Draw Lewis structure diagrams showing the formation of MgCl2.

Multiple Choice

Ionic bonds typically form between

• A metal and a nonmetal

• Two nonmetals

• Two metals

• A metalloid and a metal

Multiple Choice

Cations _______ electrons, becoming _______ charged.

• Gain; positively (+)

• Gain; negatively (-)

• Lose; positively (+)

• Lose; negatively (-)

Multiple Choice

Anions ____ electrons, becoming _____ charged.

• Gain; positively (+)

• Gain; negatively (-)

• Lose; positively (+)

• Lose; negatively (-)

Multiple Choice

Using the model for the formation of Scandium Fluoride (an ionic compound), write the chemical formula.

• Sc₃F

• Sc₃F₃

• Sc₊₃F_-1

• ScF₃