CHEMICAL FORMULA
An Intro
Recall
COMPOUND: a pure substance made up of
two or more elements that are chemically
combined
Can be broken down into simpler parts by
chemical means
ELEMENT: a pure substance made up of
one type of atom that cannot be broken
down by chemical means
Chemical Symbols
Short forms used to represent the names of
elements
Some of the elements were discovered during
ancient times hence the Latin names
Element Name
Chemical Symbol
Latin Name
Meaning of Name
Silver
Ag
Argentum
“silver”
Sodium
Na
Natrium
“sodium”
Potassium
K
Kalium
“plant ashes”
Lead
Pb
Plumbum
“lead”
Molecule
Almost all elements exist as atoms however
a few exist as MOLECULES
MOLECULE: a type of particle that is made
up of two or more atoms bonded together
Element
Chemical Symbol
# of Atoms
Chemical Formula
Hydrogen
H
2
H2
Nitrogen
N
2
N2
Oxygen
O
2
O2
Chemical Formula
A short form for writing
the name of a compound
using chemical symbols
and numbers
The chemical symbol is
written first followed by a
subscript number
Chemical Formula
Writing Chemical Formula
Write the chemical formula given the
following description:
Hydrogen sulfide is a compound that is
composed of two atoms of hydrogen and
one atom of sulfur
H2S
Now You Try…
Write the chemical formula for each
compound given the following descriptions:
a. A compound with one atom of silicon and
four atoms of hydrogen
b. A compound with three atoms of carbon
and eight atoms of hydrogen
c. A compound with two atoms of sodium, one
atom of carbon and three atoms of oxygen