Chemistry, Part 4:
Molecules &
Bonding
Science
with
Mr. Comans
In This Powerpoint:
The Importance of Molecules
What is a molecule?
How do molecules impact everyday life?
What molecules should you know?
In This Powerpoint:
Molecule Models
What is a molecular formula?
What are subscripts?
What are coefficients?
In This Powerpoint:
Bonds
How do molecules form?
What kinds of bonds should you know about?
What is an ionic bond?
What is a covalent bond?
The Importance of Molecules
Electrically neutral group of atoms
held together by chemical bonds
Molecules You Should Know
Water
H O
H
Diatomic Oxygen (the oxygen we
breathe)
O
O
Triatomic Oxygen (ozone)
O
O
O
Molecules You Should Know
Glucose (Sugar)
H
H
H H
O
C
C
C
O
H
H
O
C
OH
Carbon Dioxide
O
C
Sodium Chloride
Na Cl
O
H
H
C
C
HO
H
OH
Molecules You Should Know
Diatomic Nitrogen
N N
Diatomic Hydrogen
H H
Methane
H
H
C
H
H
Molecular Formulas
A molecular formula is a
representation of a molecule using
chemical symbols and subscripts.
A subscript is a small number after a
chemical symbol that represents the
number of atoms in each molecule.
Molecular Formulas
H2O
Water
Subscript
Molecular Formula
Carbon Dioxide
CO2
If there is no subscript
after a symbol, there is
only 1 atom of that
element in each
molecule.
Practice!
See if you can guess what elements make up each molecule,
plus how many atoms of each, based on the formula.
1.
2.
3.
4.
5.
6.
O2
CaOH
CH4
C7H5N3O6
H2CO3
H2SO4
1. Oxygen – 2 atoms
2. Calcium – 1, Oxygen – 1,
Hydrogen – 1
3. Carbon – 1, Hydrogen – 4
4. Carbon – 7, Hydrogen –
5, Nitrogen – 3, Oxygen 6
5. Hydrogen – 2, Carbon –
1, Oxygen – 3
6. Hydrogen – 2, Sulfur – 1,
Oxygen - 4
Molecular Formulas
A coefficient is a number placed in
front of a molecular formula to indicate
how many molecules are present.
H2O
Currently:
2 atoms of Hydrogen
1 atom of Oxygen
Molecular Formulas
A coefficient is a number placed in
front of a molecular formula to indicate
how many molecules are present.
2H2O
This bad boy
multiples everything
in the formula!
Currently:
4 atoms of Hydrogen
2 atoms of Oxygen
Molecular Formulas
A coefficient is a number placed in
front of a molecular formula to indicate
how many molecules are present.
3H2O
Currently:
6 atoms of Hydrogen
3 atoms of Oxygen
Molecular Formulas
A coefficient is a number placed in
front of a molecular formula to indicate
how many molecules are present.
12H2O
Currently:
24 atoms of Hydrogen
12 atoms of Oxygen
Bonds
How are these molecules held together?
Why do they form in the first place?
Recall:
H
H
O
Bonds
How are these molecules held together?
Why do they form in the first place?
H
H
O
Bonds
How are these molecules held together?
Why do they form in the first place?