Learning Goals
Students will be able to
understand the difference between
ionic/ molecular compounds and
acids
Students will be able to name and
write the chemical formula for all
types of ionic/ molecular
compounds and acids
Chemical Names and Formulas:
Overview
1. Simple (Binary) Ionic Compounds (Metals and
Non-Metals)
2. Compounds with Polyatomic Ions
3. Compounds with metals that can have multiple
charges (Multivalent)
a) using roman numerals (ie. copper (I) fluoride)
b) using the classical system (ie. cuprous fluoride)
4. Molecular compounds (2 or more non-metals)
5. Acids
a) Without oxygen b)With oxygen
1. Simple (Binary) Ionic Compounds
(Pg. 68-73, 89-90)
-
Form when a metal reacts with a non-metal
-
Made up of cations (positive ions) and
anions (negative ions)
-
Attraction holding the ions together is called
an IONIC BOND = transfer of electrons
-
Ions are attracted to each other, and not
directly attached
-
Most form a crystal lattice structure
(alternating ions extending in 3 dimensions)
Properties of Ionic Compounds
-Ionic bonds are strong, therefore:
-ionic compounds are hard, brittle solids
-have a high melting point
-Most are electrolytes (dissolve in water
which surrounds each ion, causing the
solution to conduct electricity)
NaCl dissociates
(breaks into its parts) in water
Writing the Chemical Formula for
Ionic Compounds
Chemical Formula Definition:
• shows the kind and numbers of
atoms in the smallest whole number ratio of
atoms in the substance
Examples: MgO not Mg2O2, NaCl…
Ionic Compounds: NaCl
(ratio of 1:1)
-There is not 1 atom of Na, and 1 of Cl in
NaCl
-Remember: most ionic compounds are crystal
lattice structures, so we just write the lowest
ratio of atoms
-So Na368Cl368 would be just NaCl
Writing the Chemical Formula for
Ionic Compounds (Cont’d)
What is the formula for Magnesium Chloride?
Steps:
1)Write out the ions (Mg2+ and Cl-)
2) Criss-Cross the superscript numbers (leave the
+ and – signs behind) so they become subscript #s
on the opposite side
MgCl2
*Not Mg1Cl2: don’t include any # 1’s*
You Try:
What is the formula for
aluminum oxide?
Al2O3
*charges must balance so compound
charge is neutral
Determining the name of
Ionic Compounds
What is the name of compound CaBr?
Steps:
1)Write out the name of the metal, calcium
2) Add the name of the non-metal second, bromine
3) Change the ending to ‘ide’
Calcium Bromide
You Try:
What is the name of Mg3N2
Magnesium
Nitride
2.Compounds with Polyatomic
Ions (Pg. 94-95)
Polyatomic Ion:
-an ion that consists of a stable group of 2
or more atoms acting together as a single
charged particle
-the ionic charge is shared over the entire
ion, rather than being on just one atom
Writing the Chemical Formula for
Compounds with Polyatomic Ions
What is the formula for ammonium carbonate?
Steps:
*you’ll know it involves polyatomic ions if the compound
doesn’t end in ‘ide’ with the exception of hydroxide, cyanide & thiocyanide*
1)Write out the individual polyatomic ions as
found on your green periodic table (NH4+ and
CO32-)
2) Put brackets around everything but the charges:
(NH4)+ and (CO3)23) Criss-Cross the superscript numbers only
(NH4)2 (CO3)
4) Remove brackets that have an imaginary 1
behind them
(NH4)2 CO3
You Try:
What is the formula for
Calcium chlorate?
Ca(ClO3)2
* Remember, what happens in the
brackets, stays in the brackets!
Determining the Name of
Compounds with Polyatomic Ions
What is the name of compound Mg3(PO4)2?
Steps:
1)Write out the name of the first ion (magnesium)
2) Add the name of the second (polyatomic) ion
(phosphate)
3) Leave the ending so it ends with ‘ate’ or ‘ite’
*with the exception of hydroxide, cyanide & thiocyanide*
Magnesium Phosphate
You Try:
What is the name of
Ca(HCO3)2
Calcium
Bicarbonate
3. Compounds with metals that can
have multiple charges (Multivalent)
-Many transition metals can have more than one
stable ions that can form!
-That means the naming system for these
compounds is a bit different.
-There are 2 ways of naming compounds with
metals that have multiple ionic charges
a) using roman numerals (ie. copper (I) fluoride)
b) using the classical system (ie. cuprous fluoride)
Naming Compounds with ions that can have
multiple charges using a) Roman Numerals
Write the charge of the metal in roman
numerals immediate after the metal
FeCl3
FeCl2
 Iron
(III)
Chloride
 Iron
(II)
Chloride
You Try:
What is the name of Fe2O3
Iron (III) Oxide
3+
Fe
*You know it must be
because when it reacted with
oxygen, Fe2O3 formed
This 3 is how we know it is Iron (III)
Writing the formula for compounds with
ions that can have multiple charges using
Roman Numerals
Name MnO2
-Is the Manganese ion Mn 2+ or Mn 4+ ???
-We know Oxygen’s ion is O2-, so if it
bonded with Mn 2+ we would get
Mn2O2, or MnO… so this one can’t be
-Therefore, it must be Mn 4+…
So Manganese (IV) Oxide is correct
You Try:
What is the formula for
SnO?
Tin (II) Oxide
2+
Sn
*You know it must be
because its charge has
cancelled with O2-
Naming compounds with ions that can
have multiple charges using:
b) The Classical System
The symbols of many elements are
based on their latin names (Memorize these!!):
Cu: Cuprous or Cupric
Sn: Stannous or Stannic
Pb: Plumbous or Plumbic
Fe: Ferrous or Ferric
Hg: Mercurous or Mercuric
b) The Classical System (Cont’d)
If the metal ends in ‘ous’ it is the ion
with the lower charge
If the metal ends in ‘ic’ it is the ion
with the higher charge
Naming Using the Classical
System
What is the classical name of Fe2O3?
1) Find the charge of the metal… Fe3+
or Fe2+ ?
Fe3+
2) Fe3+ is the higher charge, so it ends
in ‘ic’ , therefore, the name must be…
Ferric Oxide
You Try:
What is the classical name
for SnO?
Stannous Oxide
*You know it must be ous
because 2+ is lower than 4+
4. Molecular Compounds (Pg. 97-98)
• composed of 2 or more non-metals
• chemical formula gives EXACT number of atoms,
rather than a ratio like within an ionic crystal
• these elements are attached through a
COVALENT BOND (sharing of outer electrons)
• covalent bonds are strong
Determining the Formula of
Molecular Compounds (Pg. 97-98)
• prefixes are used to name molecular compounds
• tell us how many of each atom there are
*Note: Never use mono as a prefix for the first
element*
Example: dinitrogen pentoxide
di=2, pent=5
Therefore the formula is N2O5
You Try:
What is the formula for
oxygen difluoride ?
OF2
Determining the Name of
Molecular Compounds
Example: Nitrogen Triiodide
NI3
You Try:
What is the name for PCl5?
Phosphorus
Pentachloride
Diatomic Molecules
-formed by only 2 atoms
(either the same or different)
Example: HF:
Has 1 covalent bond, is a molecular
compound, and a diatomic molecule


7 Diatomic Elements
-7 elements form diatomic molecules with themselves
(H2, N2, O2, F2, Cl2, I2, Br2)
Mnemonic devices
If you highlight N, O, F, Cl, Br, I; six of the seven diatomic elements
on a Periodic Table - they form the number 7. The 7th is hydrogen.
Use the acronym “I Bring Clay For Our New Home”:
I = Iodine
Bring = Bromine
Clay = Chlorine
For = Fluorine
Our = Oxygen
New = Nitrogen
Home = Hydrogen
5) Naming Acids (Pg. 98-99)
All acids contain hydrogen (at the start)
HCl hydrogen chloride
or
hydrochloric acid ???
If aqueous, HCl(aq), then it’s the acid
What’s the difference between liquid and aqueous?...
Aqueous vs. Liquid?
An aqueous solution is a compound/element
dissolved in water.
A liquid is the compound/element in the liquid state.
Example:
NaCl (aq) = this is a solution of sodium chloride
dissolved in water
NaCl (l) = this is molten salt. (>700 oC )
Hydrogen chloride has the formula HCl. At room
temperature, it is a gas, which forms hydrochloric
acid upon contact with atmospheric humidity.
Naming Acids (pg. 98-100)
http://www.youtube.com/watch?v=27-aqIXf-Qg
 a)
Without Oxygen
Add the prefix ‘hydro’ and the ending
‘ic acid’
Example: HBr hydrobromic acid
You Try:
1. What is the name for HBr(aq)?
Hydrobromic acid
2. What is the name for HCN(aq)?
Hydrocyanic acid
Naming Acids (pg. 98-100)
http://www.youtube.com/watch?v=27-aqIXf-Qg
 a)
With Oxygen (Oxyacids)
Determine what ion it is made up of
Example: H2SO4(aq): H+ and (SO4)2- *sulfate ion*
If the ion ends in ate, add the ending ic acid
H2SO4 = sulfuric acid
Naming Oxyacids
ate ic acid
ite ous acid
Example #2 : H2SO3(aq)
Contains (SO3)2- *sulfite ion*
H2SO3 = sulfurous acid
You Try:
1. What is the name for HNO3(aq)?
Nitric Acid
2. What is the name for HNO2(aq)?
Nitrous Acid
Learning Goals
DID WE MEET THEM?
Can you:
1)recognize the difference between
ionic and molecular compounds?
2) How is the naming system for
molecular compounds different
from ionic compounds?
3)How can you tell if the
compound is an acid?
How do we name them?