In This Lesson:
Covalent
Nomenclature
and Acids
(Lesson 2 of 4)
Today is Thursday,
th
October 15 , 2015
Stuff You Need:
See below
Pre-Class:
What’s the name of CaCl2?
What’s the name of CO2?
Why the difference?
Also, get/take out the following:
• The flowchart-lookin’ thing I gave you days ago called
Compound Naming Chart.
• A bit of paper towel.
• Nomenclature Practice Sheet (a class or two ago).
• Periodic Tables.
Today’s Agenda
• Naming acids.
• Naming covalent (molecular) compounds.
• PRACTICE.
• Where is this in my book?
– P. 268 and following…
By the end of this lesson…
• You should be able to name molecular
compounds and acids.
Practice to Start
• #180 Names – 70-90
• Quiz Review
Acids
• We’ll learn about acids later in the year. For
now, know this:
– Acids are always aqueous (aq) – dissolved in water.
– Most acids’ chemical formulas begin with Hydrogen
(H).
• Naming them follows a predictable few steps.
Naming Acids
• First, cover the (H) and name the
anion normally.
– Sulfide.
• Next, use this key:
Example
H2
Anion Suffix
Acid Name
-ide
Hydro___ic acid
-ate
___ic acid
-ite
___ous acid
• Hydrosulfuric acid
2S
Remembering Acid Names
• “Ick, I ate it.”
– __ic is the acid suffix for stuff otherwise ending in
__ate.
• “Ite, I oust it.” OR “Riteous”
– __ous is the acid suffix for stuff otherwise ending in
__ite.
• You’ll have to come up with something for
hydro___ic acid. I’m not creative enough.
Practice
• HCl
– Cl- would be chloride, so it’s hydrochloric acid.
• H2SO4
– SO42- would be sulfate, so it’s sulfuric acid.
• HClO2
– ClO2- would be chlorite, so it’s chlorous acid.
Practice
• 180 Names – 141-150
And, of course, backwards…
• To write an acid formula from its name,
reverse the naming key.
• Then, balance the charge of the anion with
the appropriate number of hydrogen atoms.
– Hydrogen forms a 1+ charge in acids.
• Example: Nitrous Acid
– Nitrous means it must have been Nitrite (NO2-)
– To balance the -1 charge, use one H+ ion.
– HNO2
Writing Acid Formulas
• Bromic Acid
– HBrO3
• Hydroiodic Acid
– HI
• Chlorous Acid
– HClO2
• Phosphoric Acid
– H3PO4
Now then…
• Previously we learned about binary ionic
compounds.
– Compounds involving two elements bonded
ionically (because of their charge) – typically a
metal and a nonmetal.
• Now we will learn about binary molecular
compounds.
– These are compounds between two nonmetals or
metalloids.
– Also known as binary covalent compounds.
Molecular Compound Nomenclature
• The first element in the formula is named first.
– It keeps its original name.
– If there is a subscript on it, it gets a prefix.
• Don’t put “mono” in there.
• The second element is named second (duh).
– Use the element root name plus the –ide suffix.
– Always use a prefix on the second element.
• The second element is always the more
electronegative one (generally closer to
Fluorine).
Prefixes
Number
Prefix
1
Mon(o)-
2
Di-
3
Tri-
4
Tetr(a)-
5
Pent(a)-
6
Hex(a)-
7
Hept(a)-
8
Oct(a)-
9
Non(a)-
10
Dec(a)-
Naming Binary Compounds
• P2O5
– Diphosphorous pentoxide
• CO2
– Carbon dioxide
• CO
– Carbon monoxide
• N2O
– Dinitrogen monoxide
Practice – Write the Name
Compound Formula
Compound Name
N2O4
Dinitrogen tetroxide
SO3
Sulfur trioxide
CH6
Carbon hexahydride
NO2
Nitrogen dioxide
As2O5
Diarsenic pentoxide
PCl3
Phosphorus trichloride
CCl4
Carbon tetrachloride
SeF6
Selenium hexafluoride
Practice – Write the Formula
Compound Formula
Compound Name
N2I3
Dinitrogen Triiodide
P2O5
Diphosphorus pentoxide
N2O
Dinitrogen monoxide
SiO2
Silicon dioxide
CBr4
Carbon tetrabromide
SO2
Sulfur dioxide
PBr5
Phosphorus pentabromide
[Hept(a)-]
[Prefix for 7]
A Quick Break
• Occasionally, when it’s relevant, I try to stop and
remind students of “big picture” things –
important issues in our world concerning
chemistry (or other stuff).
• There is a simple compound out there that’s
become an ecological menace.
• Every creature needs some, but too much can
lead to a major ecological, societal, and
environmental disaster.
• What chemical am I talking about?
– Dihydrogen monoxide.
Dihydrogen Monoxide
• Dihydrogen monoxide is:
–
–
–
–
–
–
Fatal if inhaled.
Linked to the greenhouse effect.
A major component of acid rain.
Capable of causing severe burns.
Eroding the natural landscape.
Accelerating corrosion and rusting
of metals.
– Capable of causing electrical
failures.
– Found in the tumors of cancer
patients.
Dihydrogen Monoxide
• Despite all those problems, dihydrogen
monoxide is used in:
– Nuclear power plants
– Animal testing
– Junk food additives
– Pesticides
– Schools (including this one)
Dihydrogen Monoxide
• To relate this to our current topic, please take
a moment to write the formula for dihydrogen
monoxide. I want you to know it when you
see it:
– H2O
DHMO.org
• Visit http://www.DHMO.org for more
information.
• Also, a DHMO Material Safety Data Sheet
(MSDS).
Practice
• Nomenclature Practice Sheet – 25-42
How to Name
• How do you know what naming system to use?
• Use “ionic nomenclature” when:
– There is a metal and a non-metal.
– There are positive and negative charges.
• Use “acid nomenclature” when:
– H is in front of the formula, or the name has “acid.”
• Use “covalent/molecular nomenclature” when:
– There are two non-metals or metalloids.
– The charges are all negative.
Closure
• Remember the gas density video from
Mythbusters?
– In the video, Adam says he’s using Helium (He) to
make his voice higher. No compound there.
– However, to make his voice lower, Adam uses
Sulfur hexafluoride. What’s the formula?
• SF6
Closure
• Want practice? Want a way to do a flashcard
review of nomenclature and polyatomic ions from
your mobile device?
• Download the StudyBlue app (it’s free for
iPhone/iPad/Android) and follow this link:
– http://s.tudy.it/twatvth
– Class Code: 404963
• Alternatively, just follow it on a computer and it’ll
work the same way.
– Link is available on my Chemistry Links page.
Closure
• Nomenclature Review
• This is it, folks. The last of the nomenclature.
• Work on this quietly and on your own. We’ll
break up the sections and score them as we
go.
• This is feedback for how you’re doing.
– Take it personally.
Nomenclature Review
• Start with #1-19.
– When finished, go to the lab tables and grade one another’s work.
• Now do #20-34.
– When finished, go to the lab tables and grade one another’s work.
• Now do #35-46.
– When finished, go to the lab tables and grade one another’s work.
• Now do #47-56. #50 is tough.
– When finished, go to the lab tables and grade one another’s work.
• Now do #57-78. THIS SECTION IS LIKE YOUR QUIZ.
– When finished, go to the lab tables and grade one another’s work.
• Now do #79-81.
– When finished, go to the lab tables and grade one another’s work.