Naming Compounds
Video Notes
In this lesson, you will:
• Name both ionic and molecular
compounds when given the chemical
formula, including some hydrocarbons.
Binary Ionic Compounds
• Consist of only 2 elements. A metal and a
non-metal
• Name the positive ion first (cation)- usually
this is the metal.
• Name the negative ion (the anion),
changing the ending to –ide. (this is
typically the non-metal.)
Binary Ionic Compounds
• When metals that can form more than one
type of ion are in a compound, use a
Roman numeral in parentheses after the
name of the metal to show the charge.
• This is called the Stock system of
nomenclature (instead of using prefixes)
Some Examples
NaCl
• Cation- Sodium
• Anion- Chlorine (chloride when you change the
name)
• So the name is sodium chloride.
MgO
• Cation- Magnesium
• Anion- Oxide
• So the name is magnesium oxide.
The Stock System
• Example:
• Copper Sulfide (Cu2S)- First you look on the
periodic table or a charge chart to determine the
charge on the Sulfur ion (remember the name
changes when it is an ion to –ide)
• Sulfide ion has a charge of 2-.
• On the copper, take the overall charge and divide
by the number of ions to get the charge for each
ion. In this situation, there is 1+ for each Cu ion.
You will write copper(I)sulfide. The roman
numeral I just tells us it is the 1+ ion for copper.
The Stock System
• SnCl4 Chlorine has a 1- charge (times 4
ions for a total of 4-), so the tin (Sn) must
have a 4+ charge.
• Tin(IV)chloride is how you would write the
name.
Ternary Compounds
• Made up of 3 elements
• Name the cation then name the
polyatomic anion without changing the
ending to “ide”
Naming Ternary
Compounds
Na2SO4 Sodium Sulfate
FeCrO4 (hint: Fe is one of those metals that can
have more than one charge)
Iron(II)Chromate Since the Chromate ion has a
2- charge, the iron must have a 2+ charge…
Hence the (II).
You will get used to certain polyatomic ions so you
won’t have to look them up each time. Like SO4
is sulfate.
Remember
Ionic Compound
Composed of a cation and an anion
Transfer electrons to form a ionic compound
Molecular Compound
Composed of non-metals
Rule of Thumb
Ionic or Molecular
If the first element is a metal, use the rules for
naming an ionic compound
If the elements are all non-metals, use the rules for
naming a molecular compound
(exception: When the cation in an ionic compound is
a non metal but is the polyatomic ammonium ion
NH4.
Naming Molecular
compounds
1. The elements are named in the order they
appear in the formula.
2. Prefixes are used to denote the number of
atoms of each element in the molecule. An
exception is that the first element named is
given a prefix only if there is more than one
atom of that element in the molecule.
3. The “o” or “a” at the end of a prefix is dropped
when the word following the prefix begins with a
vowel.
4. The last element’s ending is changed to “-ide”
Molecular compound
practice
• ICl3 Iodine and Chlorine
– both are non metals
– Iodine Trichloride
• As2O5
– Both are non metals
– There are 2 ions in the Ar, so you will use a
prefix in the first element’s name.
– Diarsenic pentoxide
Naming Hydrocarbons
Alkane- CnH2n+2
Alkene- CnH2n
So review….C4H10… Alkane or Alkene?
Alkane….so the suffix is “ane”…
Prefix- 4 so it is Butane
Another?...C2H4…. Alkene so the suffix is “ene”
The prefix- 2 so it is Ethene
Chemistry Quiz
CR1. Mendeleev arranged the elements by
increasing atomic -?-.
a. Number
b. Mass
c. Theory
Chemistry Quiz
CR2. What is the electron distribution of
carbon which has and atomic number of
six?
a. 1s12s13s13p3
b. 1s22s23s2
c. 1s22s22p2
d. 1s22s23s2
Chemistry Quiz
1. A molecular compound is composed of
metals sharing electrons
a. True
b. False
Chemistry Quiz
2. What is the name of the compound
represented by the chemical formula
OF2?
a.
b.
c.
d.
Oxygen difluoride
Monoxygen difluoride
Oxygen bifluoride
Monoxygen bifluoride
Chemistry Quiz
3. What formula Fe2O3 represents the
compound ______.
a. Iron oxide
b. Iron (II) oxide
c. Di-iron trioxide
d. iron(III) oxide
Chemistry Quiz
4. When naming an alkane, the prefix
denoting one carbon in the compound is
a. methb. Ethc. Pentd. But-
Chemistry Quiz
5. In binary ionic compounds, the ending of
the anion is –ide.
a. True
b. False