What’s in the name?
Chemical nomenclature is the term
given to the naming of compounds. It is
used to identify a chemical species by
means of written or spoken words. It is
a useful means for communication
among chemists. The name of the
compound contains within itself an
implied relationship to the structure of
Lesson 1. Chemical Symbol
There are 114 known elements at present.
Among the 114 elements, 11 are known to
be gases. Some of these are oxygen, hydrogen,
nitrogen, chlorine, and helium. Elements
like neon, argon, krypton,xenon,radon, and
fluorine are very rare and are not found in large
quantities in nature. All the rest are solids.
Before the year 1814, the chemical symbols
were expressed this way:
Then Jon Jacob Berzelius (17791848), a Swedish chemist, started to use
chemical symbols. He used the initial letter
of the element’s Latin or common name in
its capitalized form as its chemical symbols
C = carbon
O = oxygen
I = iodine
This practice is still
followed today. If the two
elements start with the same
letter, two letters are used as in
Ca = calcium
Co = cobalt
What do you think is the
symbol for each of the
1. What is the correct symbol for cuprum?
2. Which of the following does NOT belong to the group?
3. Which of the following elements is a solid?
4. What is the English name of stibium?
5. Which of the following does NOT belong to the group?
Lesson 2. Chemical Formula
Chemical formulas such as MgSO4
can be divided into empirical formula,
molecular formula, and structural formula.
The chemical symbols of elements in the
chemical formula represent the elements
present in the compound. The subscript
numbers represent mole proportions of the
preceding elements. If no number is written,
it means the subscript is 1.
The Writing of Formulas
Binary Ionic Compound
(compound composed of metal and a nonmetal)
The metal acts the cation (positively-charged ion)
while the nonmetal forms the anion (negativelycharged ion). The first part of the name of an
inorganic compound is the first part of the formula.
Formula Writing of Binary
Charge – Crossing Technique
1. hydrogen chloride (you must know that
this is the common muriatic acid for
2. calcium fluoride (do you still remember
the anti tartar ingredient of your
3. sodium oxide (the substance behind the
cleansing principle of your laundry
Identifying a Compound as
Ionic or Molecular
Metals combined with
nonmetals will produce
compounds that are ionic.
Nonmetals combined with
nonmetals will produce
compounds that are
Nomenclature of Binary
A binary compound is
made up of two
Points to remember about naming
a compound from its formula
1. The order for names in a binary
compound is first the cation, then the
2. Use the name of cation directly
from the periodic table.
3. The name of the anion will be made
from the root of the element's name
plus the suffix "-ide."
Nomenclature of Acids and
For the purposes of naming
acids and bases, we will
classify these chemicals into
three categories: binary acids,
ternary acids (sometimes
called oxy-acids), and bases.
Binary acids contain hydrogen
and one other nonmetallic
element. Their names follow the
pattern of "hydroelementic acid"
where element is replaced by the
root of the name of the element.
These acids contain no oxygen.
Here are some examples.
Acids containing oxygen; most do not exist in
the same form without water:
HC2H3O2 or CH3COOH
Bases are simply named as ionic
compounds containing the hydroxide
ion. Here are some examples.
Lesson 3. Empirical and
Empirical (Simplest) formula is a
formula whose subscripts represent the
simplest whole number ratio of atoms in
a molecule or the simplest whole number
ratio of moles of each element in a mole
of the compound. The simplest formula is
usually determined by considering
experimental data, hence the name
"empirical" which means based on
Molecular formula gives the exact
number of atoms of each element per
molecule of the compound or the
absolute number of moles of each
element per mole of the compound. A
molecular formula may be reducible to
a simple formula if all its subscripts are
divisible by a common denominator.
To determine the molecular
formula of the compound,
just follow these steps:
1. Find the mass of the empirical unit.
2. Figure out how many empirical
units are in a molecular unit.
3. Write the molecular formula.
A compound with an
empirical formula of CH
has a molar mass of 78.
What is its molecular
C : 12 x 1 = 12
H : 1 x 1 = 1_
78/13 = 6
(CH)6 = C6H6
On the other hand, if the
empirical formula is asked,
simply divide the subscripts of
the molecular formula with the
greatest common factor. The
resulting SIMPLEST WHOLE
NUMBER represents the
subscript in the empirical
Example: What is the
empirical formula of the
Answer: Just divide the subscripts of
the molecular formula by the
greatest common factor.
The resulting empirical formula is NaCO2.
molecular mass C12H22O11 = 12(mass of C) +
22(mass of H) + 11(mass of O)
molecular mass C12H22O11 = 12(12.01) +
22(1.008) + 11(16.00)
molecular mass C12H22O11 = = 342.30