Chapter 5.3 Covalent Bonds
Standards:
8.3.b. Students know that compounds are formed
by combining two or more elements and that
compounds have properties that are different from
their constituent elements.
8.7.c. Students know substances can be classified
by their properties including their melting
temperature, density, hardness, and thermal and
electrical conductivity.
How Covalent Bonds form
Covalent bond: formed when two atoms
SHARE electrons
Formed between a 2 nonmetals
Molecule: neutral group of atoms joined
by covalent bonds
How many bonds?
Draw the electron dot diagrams of
Fluorine. Do this again.
 HINT: How many valence electrons does
fluorine have?
Now draw the electron dot diagrams of
2 oxygen atoms right next to each other.
 HINT: How many valence electrons does
oxygen have?
How many bonds?
Now draw the electron dot structure of 2
Nitrogen atoms.
 HINT: How many valence electrons does
each have?
Single, Double, & Triple Bonds
A single bond has 2 electrons shared.
 1 pair shared electrons
A double bond has 4 electrons shared.
 2 pair shared electrons
A triple bond has 6 electrons shared.
 3 pairs shared electrons
Molecular compounds
Compared to ionic bonds, molecular
compounds generally have lower
melting points and boiling points.
Unlike ionic compounds, molecular
compounds do not conduct electric
current when melted or dissolved in
water.
Boiling point
It takes more energy to boil ions
than molecules.
 Ionic bonds are stronger so you
need more energy to break them
up.
Conductivity
Ions have charged
particles, so they
conduct electricity.
Molecules do NOT
have charge
particles, so they
DO NOT conduct
electricity.
Unequal Sharing of Electrons
Electron sharing is like
playing tug of war. Not all
electrons are shared
equally.
 Unequal sharing of electrons
causes the bonded atoms to
have slight electrical
charges.
Polar vs Nonpolar
A covalent bond where electrons are
shared unequally is known as POLAR.
 Polar because it has poles, like the north an
south pole.
A covalent bond where electrons are
shared equally is called NONPOLAR.
Real life example:
Water is polar.
 What does polar mean?
Oil is nonpolar.
 What does nonpolar
mean?