Ionic and Covalent
Bonding
HOW DO WE TELL WHAT BONDS WE HAVE AND WHAT RULES TO USE?
Covalent Bonding

Between a Non-Metal and a Non-Metal

Only negative ions are involved: anions

Electrons from each atom are shared

No need to balance the charge

This is the situation where we use the Latin word
for the numbers
Properties of Covalent
Compounds:
 Low
melting and boiling points
 Tendency
 Do
to be soft and flexible
not conduct electricity
 There
are no electrons available to carry the current.
 When
in water, these compounds dissolve as
molecules not ions.
A
covalent solid will dissolve in covalent liquid:
“LIKE DISSOLVES LIKE”
Remember
1 = mono



2 = di

3 = tri
4 = tetra
5 = penta

6 = hexa

7 = hepta


8 = octa

9 = nona

10 = deca
Examples:
CO2
Carbon tetroxide
N5F8
triphosphorous monosulfide
That’s it for
Covalent
Bonding!
Ionic Bonding: There are a couple
different things to keep track of.
A bond between a metal and a non-metal
 Form as a result of the attraction between
positive and negative charges
 Balance out the charges
 Atoms bond in order to get a stable octet of
valence electrons
 Some ions may be unpredictable so we might
have to use roman numerals
 Polyatomic ions (I’ll explain this in a little bit)

Properties of Ionic Compounds:
 An
Ionic bond results in the transfer of electrons
 High
melting and boiling points
 Tendency
to be hard and can be split.
 Most
conduct electricity when dissolved in water or
when molten.
 When
dissolved in water the ions separate in water.
This allows for the conduction of electricity.
Ionic Properties Continued
 Ionic
solids do not conduct electricity. (must
be dissolved or molten)
 In a solid the ions cannot separate. As solids,
ionic compounds are good insulators.
 Many are soluble in water due to the fact
that water is also ionic.
 So the same rule applies as before: “LIKE
DISSOLVES LIKE” or ionic solids will dissolve in
ionic liquids
What do we list first in an Ionic
Molecule?
There are a couple of different ways to remember this:

The positive ion is listed first

The cation is listed first

The metal is listed first

The left side of the molecule can be found on the left side of
the metal-non-metal staircase
Examples of an Ionic Bond using
Monatomic Ions with one Charge:
-
These examples uses ions that are only ONE ATOM that has only ONE
OPTION FOR THE CHARGE.
Li2O
strontium bromide
What if the cation that you are
trying to use has more than one
charge?

Some cations have more than one charge.

These ions do not fall into the pattern that we
have written on our periodic tables

Most of these fall in the transition metals portion
of the periodic table
Writing the molecular formula if you
are given the name:

Use the roman numeral on the name to determine the charge of the metal

Balance out the charges
Copper(III) oxide
Lead(IV) chloride
Writing the name if you have the
molecular formula:

What is the charge of the anion and what is the total negative charge?

How many of the cation is in the molecule?

What would the charge of the cation have to be to balance out the
molecule?
PbO
PbO2
Ni2O3
And Finally…
Polyatomic Ions
Polyatomic Ions
-poly-: many



These are ions that are just like the ones that we have been using
(Cl 1-, Sr 2+, N 3-, etc) but instead
of one atom they have a few atoms
in them.
When involved in an ionic bond they
will behave the exact same way as
the other ions.
We just need to use parenthesis to help
recognize them while they are in a
compound.
Using Polyatomic Ions to Make a
Molecule

Use them exactly the same way you have used the other ions.

They don’t fall into any particular pattern on the periodic table so
you either have to memorize them or use a chart while making
bonds with them.

If you need more than one of the polyatomic ion use parenthesis.

If you only need one polyatomic ion no parenthesis are needed.
Sodium hydroxide
Aluminum hydroxide
How do you Name a Molecule with
Polyatomic Ions in it?

Use the same naming system that we used for monatomic ions that
only have one option for the charge: Name the positive side of the
molecule then name the negative side.

If the negative side in a polyatomic ion you don’t need to add
an “-ide- at the end. Just use the polyatomic ion’s regular name

Polyatomic ions only have one option for the charge
Ca(NO2)2
NaNO3