Chapter 5.3 Covalent BondsStandards:

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?