Name ___________________________
1/18/12
Covalent Bonding
Recalling dot structures:
Dot structures are easy. Let’s do some together.
Hydrogen:
Helium:
__________
Magnesium:
Lithium:
__________
Carbon:
__________
Oxygen:
__________
__________
Nitrogen:
__________
Fluorine:
__________
__________
Neon:
__________
Covalent bonds
Atoms engage in bonding to acquire a full valence shell of electrons. Let’s look at the simplest
example of covalent bonding, between two hydrogen atoms.
1) Draw two dot structures for hydrogen atoms.
2) When two hydrogen atoms form a covalent bond, each shares its valence electron with the
other for a total of two valence electrons each. Since hydrogen’s valence shell is the first energy
level, this is a full valence shell.
Draw the dot structure of two hydrogen atoms in a covalent bond
3) We can represent a shared pair of valence electrons with a line between two atoms. This
diagram, called the structural formula is how we usually draw covalent bonds.
4) Draw the dot structure of two fluorine atoms
5) Draw the dot structure of two fluorine atoms in a covalent bond. Then draw the structural
formula
Do these atoms have a full octet?
Dot structure of a water molecule
Water has a chemical formula of H2O.
Draw the dot structures of two hydrogen atoms and one oxygen atom.
Arrange these atoms in covalent bonds so that each has a full octet. Then draw the structural formula.
This is the structure of a water molecule.
Dot structure of ammonia
Ammonia has a chemical formula of H3N.
Draw the dot structures of three hydrogen atoms and one nitrogen atom.
Arrange these atoms in covalent bonds so that each has a full octet. Then draw the structural formula.
This is the structure of an ammonia molecule.
Dot structure of methane
Methane has a chemical formula of CH4.
Draw the dot structures of four hydrogen atoms and one carbon atom.
Arrange these atoms in covalent bonds so that each has a full octet. Then draw the structural formula.
This is the structure of a methane molecule.