This is a presentation for a high school chemistry 1 class on the topic of molecule names and formulas.

1. Molecular Names & Formulas
Covalent bonds happen when two atoms share one or more
pairs of electrons, causing a molecule to be formed. Because
covalent bonds are less strong than ionic bonds, covalent (or
molecular – same thing) compounds tend to be less hard. They
also have lower melting and boiling points than ionic
compounds. How will you know when a compound is
molecular?

2. Molecular Names & Formulas
A covalent bond is formed by two atoms whose electronegativities are
not vastly different. Because neither is strong enough to “take” an
electron from the other, the two atoms will share a pair of electrons.
 Below is a diatomic molecule – a molecule made when two of the same
atom join together to share a pair of electrons – one from each atom, so
each can have a full outer energy level. (Note: for hydrogen, a full outer
energy level only has 2 electrons.

http://t1.gstatic.com/images?q=tbn:FAZ1-8UhEFe1iM:http://www.mrmungin.com/chembonds

3. Molecular Names & Formulas
Molecular formulas look just like ionic formulas; They have chemical
symbols for each element with subscripts to tell how many of each
element. The molecule on the previous slide was H2, because it had two
hydrogen atoms.
 What is the formula for the chlorine gas molecule below?
 It is Cl2.
 Notice how the Lewis dot diagrams help you to visualize the sharing of
electrons.

tp://t0.gstatic.com/images?q=tbn:Ux_8ylLIm-xn8M:http://dkreutz.basd.k12.wi.us/diatomic.jp

4. Molecular Names and Formulas
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You may remember from biology class that glucose has the
formula C6H12O6. From that formula, you can tell what kinds of
atoms are in glucose, and how many of each.
See if you can find all of the atoms that make up the glucose
molecule on the illustration below.

5. Molecular Names and Formulas
Many chemicals have common names, like water. All compounds also
have chemical names.
 Review how to name ionic compounds.
 Naming covalent compounds is similar, but with prefixes to tell how many
of each type of atom.
 Water, for instance, is also known as dihydrogen monoxide. Why?


6. Molecular Names & Formulas
Prefixes on names of atoms in molecular names (chemical names of
molecular compounds) tell how many of each kind of atom. Dihydrogen
means two hydrogens are in the molecule. Monoxide means there is one
oxygen.
 The prefixes are:
 Mono
=
one
 Di
=
two
 Tri
=
three
 Tetra
=
four
 Penta
=
five
 Hexa
=
six
 Hepta
=
seven
 Octo
=
eight
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7. Molecular Names & Formulas
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You can always recognize a
molecular compound by its
name, because only a molecular
compound has a name with
prefixes.
Identify which of the names
below describe molecular
compounds:
1. sodium sulfate
2. hydrogen monoxide
3. carbon monoxide
4. ammonium hydroxide
5. carbon tetrachloride
6. dinitrogen trioxide
7. calcium carbonate

Hint: If there is only one of the
first atom listed in a molecular
formula, “mono-” is not needed.
Mono- is not normally used for
the first named element.

Sodium sulfate if ionic. You can tell by the name
of the polyatomic ion ending in -ate.
Hydrogen monoxide is molecular. The monogives it away.
Carbon monoxide is molecular.
Ammonium hydroxide is ionic.
Carbon tetrachloride is molecular.
Dinitrogen tetroxide is molecular.
Calcium carbonate is ionic.
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8. Molecular Names & Formulas
Write the name and formula of each.

9. 
The first diagram was carbon
tetrahydride. What is its formula?

This diagram had three carbons and
eight hydrogen atoms, so it is
tricarbon octahydride, A.K.A.
. What is its formula?
propane

The diagram showed carbon dioxide.
What is its formula?

The last diagram had two hydrogen
atoms and one oxygen atom, so it is
___hydrogen monoxide, A.K.A.
water.

10.  Try
the tutorial listed below for more.
http://www.wiley.com/college/chem/spencer053872/tutorial/formulas
 Take
notes and review your notes.