CP Chemistry

Covalent Bond Exercise

INTRODUCTION: In molecules and polyatomic ions the atoms are held together by covalent bonds. These are bonds formed when atoms share a pair of electrons. The sharing of the pair of electrons makes each of the atoms apparently have the same number of electrons in its outer shell as its nearest noble gas neighbor (usually 8). The purpose of this exercise is to help you see how covalent bonds are formed and how these bonds allow groups of atoms to become molecules.

MATERIALS:

scissors

glue or tape

cut-outs of atoms showing their outer shell electrons

PROCEDURE:

1. Cut out the figures for the atoms as you need them.

2. For the compounds listed below place the correct atom figures together on a piece of notebook paper so that the "electron(s)" sticking off one cut-out is paired with the electron sticking off another. This pairing simulates a covalent bond.

3. In the compounds in this exercise with more than one carbon atom, each carbon atom is attached to another carbon atom. Remember that every electron sticking off an atom must be paired with one from another atom. There must be no unpaired electrons. If there are, try another arrangement for the atoms. There is only one correct arrangement for each molecule.

4. After correctly putting the atoms together, glue or tape them into position.

5. Below each molecule model you have made, write the correct electron-dot diagram and the correct chemical formula for the compound.

COMPOUNDS

a)1 carbon, 4 hydrogen

b)2 hydrogen

c)1 phosphorus, 3 hydrogen

d)2 fluorine

e)1 carbon, 4 hydrogen, 1 oxygen

f)1 oxygen, 2 fluorine

g)2 hydrogen, 1 sulfur

h)1 phosphorus, 3 chlorine

i)1 nitrogen, 3 hydrogen

j)1 hydrogen, 1 chlorine, 1 oxygen

k)2 carbon, 6 hydrogen, 1 oxygen