Name:_____________________________________________________________________________________________________________
Covalent Bonding and Bond Type Notes (Unit 5.3 and 5.4)
COVALENT BONDING

Remember in ionic bonding a metal gives away one or more electrons to a non-metal.

Many compounds do not contain a _________________and are made up of elements that do not
_____________ away electrons. So what do they do??

Non-metal atoms will ____________________ electrons to form _________________ bonded ______________.
SHARING ELECTRONS

Atoms share electrons to get the nearest _____________ gas electronic configuration

Some elements only share one electron. Like H and Cl

Many share only ___________ - if they share all they will exceed their “octet.” Like nitrogen in NH3 and oxygen
in H2O

Atoms of elements in the ______ period onwards can _____________ their “octet” if they wish as they are not
restricted to eight electrons in their “outer shell.” Like phosphorus in PCl5 and sulfur in SF6.
MOLECULES

Unlike ionic compounds that form large ____________ lattices, covalent
compounds form individual _________________.

In other words, molecules are neutral collections of atoms held together by
covalent bonds.

The formula for an covalent compound is known as a _______________ formula

It represents the ______________________ number of each type of atom in the
molecule.
MORE ON COVALENT BONDING
•
When a covalent bond occurs, each atom contributes an electron to make
a _____________________ pair.
•
In this diagram the electrons from the Hydrogen have been represented
with a cross.
•
Those from the oxygen are represented by a dot.
•
In reality all electrons are ________________________________.
Name:_____________________________________________________________________________________________________________
EXAMPLE 1

Try drawing the “dot cross” diagram for methane (CH4). Hint: Draw the atom that wants to share the most in the
middle.
EXAMPLE 2

Try drawing the “dot cross” diagram for chlorine gas (Cl2).
DOUBLE AND TRIPLE BONDS

Each oxygen needs to share two electrons to have a full octet.

The bond that forms between the oxygen atoms is known as a _____________________ bond.

In Nitrogen gas (N2), each nitrogen needs to share three to have a full octet. This is called a triple bond.
LEWIS DOT DIAGRAMS

Molecules of covalent compounds can also be represented by Lewis Dot Diagrams.

You need to know the number of _______________________ electrons for each element.

Non- shared electrons are represented as _______________.

Each shared pair of electrons are represented by a ________________ connecting the two atoms.
EXAMPLE 1

Draw the Lewis Dot Diagram for phosphorus trichloride (PCl3).

Hint: draw the atom that that is least __________________________ in the middle (it is also the one that wants
to share the most!)
Name:_____________________________________________________________________________________________________________
EXAMPLE 2

Draw the Lewis Dot Diagram for hydrogen cyanide (HCN).

Hint: hydrogen needs two electrons, carbon and nitrogen each want a total of eight. Draw the one that is least
________________________________ in the middle (it is also that one that wants to share the most!)
RESONANCE

Some molecules cannot be represented adequately by a ________________ Lewis structure.

This is known as ________________________.

Example: ozone (O3)

The actual structure is an __________________ of the two structures above.
COVALENT COMPOUND PROPERTIES

Melting point- _______________:

Most covalent substances are _______________________ or gases.

Solid covalent substances have a low melting point.

Covalent bonding produces _______________________ molecules.

The attraction between these molecules is _______________________ compared to the attraction between
ions in a crystal lattice.

Not a lot of _____________________________ is require to overcome these minimal attractions.

Conductivity- __________________:
◦
Electrons are ___________________ in covalent compounds.
◦
Therefore atoms don’t become oppositely charged __________________; they remain neutral.
◦
______________________ atoms are unable to conduct electricity because they won’t travel towards
the cathode or the anode.
POLAR AND NON POLAR COVALENT BONDS

Although atoms often form compounds by sharing electrons, the electrons are not always shared
_________________.

When two identical atoms are bonded the electrons are shared equally. Like in F2 below.
Name:_____________________________________________________________________________________________________________

But in HF, Fluorine pulls harder on the electrons it shares with hydrogen
than hydrogen does.

Therefore, the fluorine end of the molecule has more electron
___________________ than the hydrogen end.

Nonpolar Covalent: ____________________ shared electrons

Polar Covalent: _____________________ shared electrons

◦
Part of the molecule has a partially __________________ charge.
◦
Part of the molecule has a partially negative ____________________.
Bonds are ________________________ completely nonpolar because one atom usually attracts electrons more
strongly than the other.
DIPOLES

A dipole is an _________________________ distribution of electrons.

This causes a partially positive electrical charge and a partially negative
electrical charge to form on part of a molecule.

In other words, it is a __________________ with a partially positive end and a
__________________ negative charge at the other end.
IONIC, NONPOLAR, OR POLAR?

The type of bond that forms depends on the ____________________________________!

Remember electronegativity is the ____________________ of an atom for the ___________________ electrons
in a compound.

The greater the difference in electronegativity between the atoms, the more _________ character the bond has.

Take the higher electronegativity and ______________ the lower electronegativity to get the _______________.
•
difference > 1.7 → Ionic
•
difference < 0.3 → Nonpolar covalent
•
1.7 > difference > 0.3 → Polar covalent
 What type of bond will form between Potassium and Chlorine?
K: 0.82, Cl: 3.16