Covalent bonds form between non-metallic elements by atoms sharing electrons so that each atom has a full outer valence shell. The number of covalent bonds an atom can form depends on the number of electrons it needs to fill its outer shell - carbon forms 4 bonds, nitrogen 3 bonds, oxygen 2 bonds, and fluorine 1 bond. Chlorine, with 7 valence electrons, forms diatomic chlorine gas molecules where each chlorine shares one pair of electrons in a single covalent bond. Covalent compounds have low melting and boiling points due to weak attractions between molecules, most are not soluble in water as they do not conduct electricity, and they exist as solids, liquids or gases made of molecules rather than crystalline ion

1. Compounds and
Bonding
Covalent Bonding

2. Covalent bonds form between atoms of
non-metallic elements.
In a covalent bond, the octet rule is
satisfied by atoms sharing electrons so
that each can have a full outer valence
shell.
Shared pair of electrons forms
covalent bond between hydrogen
and oxygen in this water molecule

3. The number of electrons required to fill the outer shell
indicates how many covalent bonds an atom can form. For
example, to satisfy the octet rule . .
Carbon will form 4 covalent bonds
Nitrogen will form 3 covalent bonds
Oxygen will form 2 covalent bonds
Fluorine will form 1 covalent bonds
Neon will form 0 covalent bonds

4. Chlorine has 7 valence electrons, and requires one
more to complete the outer shell
We know chlorine gas is a diatomic molecule and has the
formula Cl2. A molecule of chlorine gas consists of two
atoms held together by a covalent bond.
Shared pair of electrons
(single covalent bond)
Cl Cl Cl Cl

6. Try these examples. Use dot and cross
diagrams to show the covalent bonding in:
HCl (hydrochloric acid) CH4 (methane)
sharing
Start with the Lewis dot diagrams for each element involved.
Combine the diagrams to form the molecule.

7. Try these examples. Use dot and cross
diagrams to show the covalent bonding in:
HCl (hydrochloric acid) CH4 (methane)
In a covalent bond, the shared electrons are counted in both
atoms valence shells when applying the octet rule.

8. Simplified
HCl (hydrochloric acid)
CH4 (methane)
Lewis dot structures of molecules show all the bonds (the
valence electrons)

9. Multiple covalent bonds
Atoms joined by covalent bonds can share
more than one pair of electrons. Consider a
molecule of oxygen O2

10. Multiple covalent bonds
Two shared pairs = ONE double covalent bond

11. Try to draw the covalent bonding in CO2

12. Try to draw the covalent bonding in N2
Three shared pairs = ONE triple covalent bond

13. Complete the bonding and naming worksheets

14. Polyatomic ions
Polyatomic ions are groups of atoms held
together by covalent bonds but have an overall
electrical charge
-1
for example
the nitrate ion
NO3 -1

15. Complete the polyatomic ion worksheet
(NH4)2CO3
?
Ammonium
carbonate
CuCl
?
Copper I chloride
Ca(NO3)2
?
Calcium nitrate

16. Properties of Covalent Compounds
Physical Ionic Covalent
Property Crystal Molecular
Very high
Melting and boiling
Strong attractions
points
between ions
Most ionic
Solubility in water compounds are
soluble in water.
Yes when dissolved
Conduct electricity
in water or melted
Hardness Very brittle
Solids with
Structure geometrical
arrangement of ions

17. Properties of Covalent Compounds
Physical Ionic Covalent
Property Crystal Molecular
Very high Low
Melting and boiling
Strong attractions Weak attractions
points
between ions between molecules
Most ionic
Only polar molecules
Solubility in water compounds are
dissolve in water.
soluble in water.
Yes when dissolved
Conduct electricity Do not conduct
in water or melted
Hardness Very brittle Not brittle
Solids with
Solid, liquid, gas
Structure geometrical
made of molecules
arrangement of ions