Chemistry SM-1131
Week 6 Lesson 2
Dr. Jesse Reich
Assistant Professor of Chemistry
Massachusetts Maritime Academy
Fall 2008
Class Today
• Molecules, Compounds, Nomenclature
• No Class on Friday, but you’ll have to make one up
later, enjoy the weekend
• New Material: Polyatomic anions, Molecular
Compounds, Acid Names, Formula Mass
What does that mean?
• Don’t do homework with friends in your
room.
• Don’t hang with friends when you have to do
work.
• Don’t think about work when you are chilling
with friends.
• If you got less than a raw 70 you really have to
do the homework or risk failing this course
• You won’t pass this class just listening
Compounds
• Joseph Proust- 1754-1826
• Law of Constant Composition: All samples of a
given compound have the same proportions
of their constituent elements
• Every molecule of water has H2O, every
molecule of sugar is C6H12O6
What’s it mean
H is the symbol
O is the symbol
2 is how many Hs there are
.
How many Os?
More complicated…
•
•
•
•
•
•
•
Mg(NO3)2
There is one Mg
There are 2 groups of (NO3)
In each NO3 there is 1 N and 3 O
The math 2 * 1N = 2N
The math 2 * 3O = 6O
Total formula= Mg1N2O6
Atomic Elements
• Noble Gases, many metals exist simply as just
their element
Molecular Elements
• Many elements are not stable enough to exist
on their own without forming molecules:
• H = H2, N = N2, O = O2, F = F2, S = S8, Cl = Cl2,
• Br = Br2, I = I2
• These are so unstable they need to form
molecules to exist, they are molecular
elements
2 Compound Types
• Ionic Compounds: Are between two or more
ions, most of them are between a metal and a
non-metal
• Molecular Compounds: Are between 2 or
more non-metals
Compound Types
Ionic: Metal and a non-metal
Molecular: 2 non metals
Memorize this Table
•
•
•
•
•
•
•
•
Group 1= +1
Group2= +2
Group13= +3
Group14= + or – 4
Group 15= -3
Group 16 = -2
Group 17= -1
Group 18 = No Charge Ever!
Ionic Compounds
• They are overall neutral, but each component
has a charge. So, we have to make sure that
charges are balanced.
Ionic Compound Making
•
•
•
•
•
1- Write their symbols
2- Write their charges to the upper right
3-Switcheroo
4- (Reduce)
MEMORIZE THIS!
Naming Ionic
Compounds
• Hold UP!
• Ionic Compounds have 1 naming system
• Molecular compounds have a 2nd naming
system that works differently
• Ionic Compounds are between metals and
non-metals
Naming Metals
• Alkali, alkaline earth, and group 3 metals are
easy to name in compounds when saying their
names out loud. Just use what you see on the
periodic table.
• Al is aluminum, Na is sodium, Mg is
Magnesium
Transition Metals
• Alkali metals are easy. The charge is always 1.
Alkaline earth metals are easy the charge is
always 2. Group 13 metals are easy the
charge is always +3.
• Transition metals, lanthanides, actinides, and
all the other metals are trickier. There are
multiple charges they can have and multiple
names for the metals depending on their
charge.
T.M. Example
• Iron can exist in stable forms with a +2 or +3
charge. We write the symbol as as Fe+2 and
Fe+3 or Fe(II) and Fe(III) or Iron (II) and Iron (III)
• Copper typically has a +1 or +2 charge. We
will write it as Cu+1 or Cu+2e or Cu(I) and Cu (II)
or Copper (I) and Copper (II)
Transition Metals
• Chemistry is old. We’ve actually gone through
2 naming systems for transition metals.
• The old system had certain names for certain
charges. Fe+2 and Fe+3 were called ferrous and
ferric. We won’t use those names in here, but
you should at least read the list and be
familiar.
Naming Ionic
Compounds
• The non-metal in ionic compounds gets it’s
name changed.
• Chlorine becomes chloride
• Oxygen becomes oxide
• Nitrogen becomes nitride
• Fluorine becomes Fluoride
• Sulfur becomes Sulfide
• Iodine becomes Iodide
All the way through
• Magnesium and Nitrogen form a compound
what is it’s formula and name?
• MgN
• Mg+2N-3
• Mg3N2
• Can’t reduce
• Magnesium Nitride
What about Iron (II) and
Nitrogen
•
•
•
•
•
Fe and N
Fe+2 and N-3
Fe3N2
3:2 doesn’t reduce
Iron (II) Nitride
New Material
• Polyatomic Ions
• Ionic Compounds are between metals and
non-metals, AND metals and polyatomic
atoms
• Poly=Many
• Atomic= Atoms
• Polyatomic= many atoms
Polyatomic Anions
•
•
•
•
•
Compounds still work basically the same way
1- Symbols (keep the parenthesis)
2- Charges
3- Switcheroo
4- Reduce
Example
• Sodium and Carbonate combine to make a
compound. What’s the formula and charge?
• Na & (CO3)
• Na+1 and CO3-2
• Na2(CO3)
• Metal First polyatomic ion second
• Sodium Carbonate
Example 2
• Magnesium and Phosphate come together to
form a compound. Formula and charge?
• Mg & (PO4)
• Mg+2 & (PO4)-3
• Mg3(PO4)2
• Metal first polyatomic ion second
• Magnesium Phosphate
Example 2 cont.
•
•
•
•
•
•
•
•
Mg3(PO4)2
There are 3 Magnesium atoms
There are 2 PO4 groups
Each PO4 group has 1 P and 4 O
So, we have to multiply:
2x 1P = 2P
2x 4O = 8O
Total: Mg3P2O8
Example 3
• Iron (III) and Nitrate form a compound.
What’s the formula and name?
• Fe(III) & (NO3)
• Fe(III)+3 & (NO3)-1
• Fe(III)1(NO3)3
• Iron (III) nitrate
• Formula = Fe(III)1N3O9
Example 4
• Ammonium and Permanganate form a compound.
Formula and Name?
• (NH4) & (MnO4)
• (NH4)+1 & (MnO4)-1
• (NH4)1(MnO4)1
• Ammonium Permanganate
• This guy is a rarity because the non-metal thing is the
cation and the metal thing is the anion. Polyatomics
can act a little differerntly than metals or non-metals
that are just by themselves.
Polyatomics to
Memorize
• Table 5.6 page 138
• Make note cards. They are all fair game.
Molecular Compounds
• Ionic compounds are between metals and
non-metals (or polyatomic ions)
• Molecular compounds are between 2 or
more non-metals
Molecular Compounds
• Two different naming systems. DON’T
CONFUSE THEM!
• This system is just for molecular compounds.
• Molecular compounds have 2 or more nonmetals in them
Molecular
Nomenclature
• The naming systems for the simple ones works
like this:
• 1-Prefix
• 2-First element (somewhat alphabetical)
• 3-Prefix
• 4-Second element
• 5-change the ending of the second element to
-ide.
What are the prefixes
• MEMORIZE THESE!
•
•
•
•
•
•
•
•
Mono-1
Di-2
Tri-3
Tetra-4
Penta-5
Hexa-6
Hepta-7
Octa-8
Example
•
•
•
•
•
•
•
Here’s a formula: N2O4. What’s the name?
Di
Nitrogen
Tetra
Oxygen
Oxide
Dinitrogen tetraoxide
Example 2
• SF6
• Mono (If mono is the very first one you don’t
have to use it).
• Sulfur
• Hexa
• Fluorine
• Fluoride
• Sulfur Hexafluoride
Example 3
•
•
•
•
•
•
•
CO2
Mono (drop it)
Carbon
Di
Oxygen
Oxide
Carbon Dioxide
Acids
• Acids are things that create H+ ions when
dissolved in water. They are typically bitter
and sour tasting. Most acids can dissolve
metals.
• They are combinations of H+ atoms with
anions
Acid Types
• Binary Acids
• Oxyacids
Binary Acid Names
• Binary Acids are a combination of 2 things.
Hydrogen and one other non-metal
• Naming them is simple
• 1-Hydro
• 2-Base name of non-metal
• 3-change the ending of the non-metal to –ic
• 4-Add the word acid at the end
Binary Acid names
•
•
•
•
•
•
HBr
1-Hydro
2-Brom
3-ic
4-Acid
Name= Hydrobromic acid
Binary Acid Names
•
•
•
•
•
•
HCl
1-Hydro
2-Chlor
3-ic
4- Acid
Name= Hydrochloric Acid
Oxyacid Names
• Oxy Acids are built around compounds that
have oxygen containing polyatomic anions in
them.
What polyatomic anions
make sense?
•
•
•
•
•
•
•
Phosphate (PO4)
Phosphite (PO3)
Chlorate (ClO3)
Chlorite (ClO2)
Nitrate (NO3)
Sulfate (SO4)
Sulfite (SO3)
Oxyacid naming with
-ate
• 1-Name of the polyatomic acid
• 2-change the ending to –ic (sometimes needs
a fudge factor)
• 3-add the word acid
Oxyacid Naming
• Phosphate makes an acid. What is the name and
formula?
• 1-Phosphate
• 2-turns into Phosphoric
• 3- add acid
• Name= Phosphoric Acid
• 1-H (PO4)
• 2-H+1(PO4)-3
• 3-H3(PO4)1
• Can’t reduce
Naming Oxyacids with
-ite polyatomic anions
• 1-Write the anion name
• 2-Change the ending to –ous (might need a
fudge factor)
• 3- add the word acid
Oxyacid Naming with
-ite polyatomic anions
• The polyatomic anion sulfite forms an oxyacid. What
is the name and formula?
• 1-Sulfite
• 2- Change to Sulferous
• 3- add Acid
• Name= Sulferous Acid
• H (SO3)
• H+1 (SO3)-2
• H2(SO3)1
• Can’t reduce
Molecular Mass
• To figure out molecular mass you have to
know the atomic mass.
• Let’s start easily
• Ne- it exists by itself and doesn’t form
molecules. It’s mass is just the atomic mass of
Ne, which is 20.18
Simple Molecule Mass
• The mass of N2 is going to be twice the mass
of 1 atom of N
• So, if N has an atomic mass of 14.01, then N2
must have a mass of 2x14.01 or 28.02
Molecular Mass
• Ozone has the formula O3, what is it’s
molecular mass
• 1 Oxygen has a mass of 16.00
• 3x(16.00) has a mass of 48.00 amu
More Complex Masses
• Water has the formula H2O
• The molecular mass is going to be from 2H
atoms and 1 O atom, so
• 2x(1.0079) + 1x(16.00)= 18.0158amu
Sugar
• C6H12O6
• 6(12.01) + 12(1.0079) + 6(16.00)= ???
• Homework due Monday
• Work on your Wikis the due date is coming up
• Test coming in two weeks