Writing Chemical Formulas
A compound is a substance made up of a
definite proportion of two or more elements.
A molecule is formed when two or
more atoms join together chemically.
A compound is a molecule that contains at
least two different elements. All compounds
are molecules but not all molecules are
compounds.
A chemical formula tells us the number of
atoms of each element in a compound. It
contains the symbols of the atoms of the
elements present in the compound, as well
as how many there are for each element in
the form of subscripts.
How to write chemical formula?
1. Ionic Bond
A type of chemical bond where two atoms or
molecules are connected to each other by
electrostatic attraction.
Happens between a metal and non-metal
elements or metal and polyatomic ions.It
involves transfer of electrons.
How to write chemical formula given
the chemical name?
1. Identify the elements.
2. Write them in ion form.
3. The total charge of a compound is 0.
Example: (ionic compounds)
1. Sodium Chloride
2. Magnesium Chloride
Example:
3. Lithium Phosphide
4. Aluminum Oxide
5. Potassium Nitride
6. Calcium Chloride
7. Calcium Oxide
How to write chemical formula?
2. Covalent Bond/Molecular Bond
is a chemical bond that involves the sharing of
electron pairs between atoms.
Usually happens between non-metal elements
or metal and polyatomic ions.
How to write chemical formula?
1. The compound name will tell how many of
each element a compound has.
2. The second name has “ide” in the end.
3. The prefix mono will not be written on the
first element. (if there is only one atom)
Prefixes for covalent compounds:
Number
of Atoms
1
2
3
4
5
Prefix
Mono
Di
Tri
Tetra
Penta
Number
of Atoms
6
7
8
9
10
Prefix
Hexa
Hepta
Octa
Nona
Deca
Example:
1. Dichlorine Monoxide
2. Dinitrogen Tetraoxide
3. Carbon Monoxide
4. Carbon Dioxide
5. Tetraphosphorous Decasulfide
6. Hydrogen Chloride
7. Dinitrogen Tetraoxide
Writing Formulas with Polyatomic Ions
What are Polyatomic
Ions?
These are group of atoms which has a net
charge of either positive or negative.
These are charged molecule (ion)
composed of 2 or more non-metals.
Writing Formulas with Polyatomic Ions
1. Calcium Nitrate
2. Ammonium Nitride
3. Sodium Carbonate
4. Amonium phosphate
5. Magnesium Phosphate
6. Ammonium Acetate
7. Manganese (II) Hydroxide