Ionic Compounds
Section 3.0 (pg. 138-153)
Naming Compounds

In 1787, Guyton de Morveau created a naming
system



Used the chemical name for each element in the
compound
Metal was always listed first
E.g., zinc and oxygen = zinc oxide

Not only do elements have universal symbols that are
recognized world-wide, but compounds are also
named according to global guidelines.

The international Union of Pure and Applied
Chemistry (IUPAC) is an organization of scientists
responsible for setting standards in chemistry.

IUPAC makes recommendations on how compounds
should be named.

There are rules to naming compounds.
Language
Symbol
English
Name of
element
hydrogen
French
hydrogene
H
German
wasserstoff
H
Italian
idrogeno
H
Portuguese
hidrogenio
H
Spanish
hidrogeno
H
H
What’s in a Chemical Formula?
Symbol for
chemical element
hydrogen
Symbol for
the element
oxygen
H2O(l)
The small number
here means 2
atoms of
hydrogen
(subscripted
number)
No small
number
means 1
atom of
oxygen
This means the
state of the
compound:
(l)- liquid
(g)- gas
(s)- solid
(aq)- aqueous

A chemical formula uses symbols and numerals
to represent the composition of a pure substance.
Each symbol in a chemical formula represents an
atom of an element.

If there is more than one atom of an element, a
small number written below the line (a subscript)
follows the elements symbol

The subscript shows the number of atoms.
Law of Definite Composition
 The
Law of Definite Composition tells
us that every pure substance has a fixed and
definite composition.
 Ex: (H2O)
ALWAYS contains two atoms of
hydrogen for each atom of oxygen.
Formula
N2
CH4
5Ca(OH)2
Elements
# of atoms
of each
element
per
molecule
Total # of
atoms per
molecule
# of
molecules
Total # of
atoms
To Do. . .
 Analyzing
Chemical Formulas Worksheet
Ions
 When
at atom gains or loses electrons,
the atom is no longer neutral. It has
become an ion.
 An
ion is a particle or group of particles
with a positive or negative charge.
Properties of Ionic Compounds
Formed from metallic and nonmetallic elements
Forms ions in solution
Conducts electricity
Solid at room temperature
A sodium atom contains 11 protons and 11
electrons.
 If sodium loses an electron, it has 11 protons
but only 10 electrons, so the sodium ion is
positive.
 The chlorine has gained an electron leaving it
with a slight negative charge.
 The two elements now form a compoundsodium chloride (NaCl) or table salt!

 Conductivity
is the ability of a substance
to carry an electrical current.
 Charged
particles (positive or negative)
can carry an electrical current through
water.
How do we name ionic compounds?
1.
Name includes both elements in the
compound, with the name of the metallic
element first.
2.
Non-metallic element is 2nd.
Its ending is changed to “-ide”
Name these ionic compounds below:
1.
NaCl
2.
NaF
3.
LiCl
4.
ZnS
Ions
 Atoms
of most elements will either gain
or lose one or more of their outermost
electrons.
 Ionization:
 Process
of gaining or losing electrons
Ions
 Cations
(+)
 Positively charged ions
 Form when metal atoms lose electrons
 The lost electrons usually move to
another atom.
Ions
 Anions
(-)
 Negatively charged ions
 Form when non-metal atoms gain
electrons.
 NAME
 Use
CHANGES:
first part of name and change the
last part to “-ide”
Ions
 Metal
atoms tend to form cations by
losing electrons.
 Non-metals tend to form anions by
gaining electrons
 Atoms gain or lose electrons so that they
have the same number of electrons as the
nearest noble gas. E.g., oxygen
 Makes them more stable
 Atoms = Neutral AND Ions = Charged
Where is the ionic charge of an element?
Small positive or negative numbers
 Top right-hand corner, under the atomic mass.

GROUP #
IONIC CHARGE
1
1+
2
2+
17
1-
16
2-
15
3-
Ionic - Chemical Formula

Ex: calcium chloride
 STEP
1) Write the symbols for each of
elements:
 Metals are always written 1st
 Non-metals are written 2nd
 Ca
Cl
Ionic - Chemical Formula

Ex: calcium chloride
 STEP
2) From the top right corner of
your periodic table write down the ion
charge for each element.
 Ca+2
Cl-1
Ionic - Chemical Formula

Ex: calcium chloride
 STEP

3) Balance the ion charges.
Ca2+ and Cl-1 + Cl-1
Ionic - Chemical Formula

Ex: calcium chloride
 STEP
4) Combine the element symbols
WITHOUT the ion charges and include
subscripts indicating the number of each
element.
 CaCl2
REMEMBER!!
 When
you are writing the chemical
formulas for IONIC COMPOUNDS, you
need to switch charges and write them
as the subscript!!
 EXAMPLE:
 MgCl2
magnesium chloride
Let’s try these:
1.
magnesium oxide
2.
lithium chloride
3.
calcium chloride
4.
sodium sulfide
Chemical Naming and Formulas Review
 Read
Section 3.1 (pages 139-142)
 Check and Reflect questions #1-4
C&R pg. 143 #1-4
The chemical formula will tell you:
1.
a)
b)
c)
d)
The elements in the compound
How many atoms of each element
How many molecules
The state of the compound
2.
a)
b)
c)
d)
e)
hydrogen, fluorine
lithium, oxygen
potassium, phosphorus
nickel, oxygen
mercury, chlorine
C&R pg. 143 #1-4
3.
a)
b)
c)
d)
e)
2 atoms
2 atoms
5 atoms
5 atoms
2 atoms
a)
b)
c)
d)
Na2S
AlF3
O2
C6H12O6
4.
Practice: Read pages 144-147
MnO2
 potassium fluoride
 MgBr2
 CaO
 Na2SO4
 NaOH
 iron (II) oxide
 Fe2O3

To Do:
 Ionic
Compound Worksheet
 TONIGHT:

Pg. 149 C&R #3-8
Molecular Compounds
Section 3.3 (pages 150-153)
Properties of Molecular Compounds
 Non-metal
+ non-metal
 Uses prefixes for naming
 Can be solid, liquid or gas at room temp.
 Poor conductors (insulators)
 Low melting/boiling points
 Weak bonds
MOLECULAR COMPOUNDS
A
molecule is the smallest independent
unit of a pure substance and is generally a
cluster of atoms joined together.
 Diatomic
molecules are molecules
made of two atoms of the same element.
The Rule of “-gen”
 These
are all of the DIATOMIC
elements in the periodic table
 Includes:
 All
of group 17 (halogens)
 oxygen
 nitrogen
 hydrogen
 The
BONDING between ATOMS is
strong, but the attraction between
MOLECULES is weak.
 When
you melt or vaporize a molecular
compound, you must supply enough
energy to overcome the attraction
between the molecules.
WATER
MOLECULES
Hydrogen
atom
Oxygen
atom
Hydrogen molecules
Oxygen
molecules
Naming molecular compounds!
What is this? CO2
1. Write the entire name of the 1st element
 carbon
2. Change the ending on the name of the 2nd
element to
“-ide”
o oxygen  oxide
3. Use a prefix to indicate the number of each
type of atom in the formula
 carbon dioxide
PREFIXES
o
o
o
o
o
o
o
o
o
o
1- mono
2- di
3- tri
4- tetra
5- penta
6- hexa
7- hepta
8- octa
9- nona
10- deca
Molecular - Chemical Naming

Ex: Water – H2O(l)
H2O(l)
prefix + non-metal1
prefix + non-metal2
(ide ending)
Molecular - Chemical Naming

Ex: Ammonia – NH3(g)
 NH3
(3 hydrogen atoms)
 nitrogen
trihydride
Molecular - Chemical Naming

Ex: Ammonia – NH3(g)
 EXCEPTION
1) :
 When there is only one atom in the first
element in the prefix mono is NOT used.
______nitrogen
trihydride
Molecular - Chemical Naming
 EXCEPTION
2)
 Diatomic Elements – All naturally form
molecules with two atoms. Do not use
prefixes!
H2(g)
 O2(g)

 Applies
hydrogen
oxygen
to: N2, H2, O2, and all Halogens
(Group 17)
Let’s do a couple examples:
1.
SO
2.
CCl4
3.
S3O6
4.
P4O10
Name these:
1.
H2O2
2.
HCl7
3.
CO
4.
SO2
5.
H2O
If you are changing from the written name
to the symbol:
1.
Write the symbols for the elements in
the same order as they appear in the
name
2.
Use subscripts to indicate the numbers
of each type of atom
Molecular - Chemical Formula

Ex: carbon dioxide
 STEP
1) Write the symbols for each of
the elements:
C
O
Molecular - Chemical Formula

Ex: carbon dioxide
 STEP
2) Change the prefixes into
numbers and write them in as
subscripts.
C
O2
Let’s do these:
1.
carbon tetrachloride
2.
silicon dioxide
3.
sulfur dioxide
Practice:
1.
2.
3.
4.
5.
6.
7.
8.
C3H8
CCl4
dinitrogen monoxide
NF5
heptaphosphorus nonabromide
N5I8
carbon hexaoxide
S8F3
To Do:

Naming Molecular Compounds Worksheet

For Homework:


Read Section 3.3 (pages 150-153)
Check and Reflect questions #1-5
Ionic vs. Molecular
Section 3.2 and 3.3
How can you tell if a substance is ionic or
molecular?


Look at the first element in the compound
If it is a metal = ionic



NO prefixes
Balance charges
If it is a non-metal = molecular


Prefixes
Do not need to balance charges = use subscripts to tell how many
of each atom is present
Ionic or Molecular?

NaBr

nitrogen trihydride

magnesium chloride

carbon tetrachloride

H20

aluminum chloride
Fill in the following table!
Ionic or
Molecular
1
2
Chemical
Formula
NaBr
P5H9
3
calcium sulfide
magnesium bromide
lithium phosphide
4
5
6
Name of Compound
CO2
Remember to always decide if the substance is ionic or
molecular before naming it!
To do:



Review: Ionic & Molecular
Topic 4-6 Review – Due Thursday!
Ionic vs. Molecular Lab- Thursday!