Chemical Bonding – Combining Capacities (Valences or Oxidation States)
Every atom wants to have 8 electrons in its outer orbital. It has two options, either steal
those electrons or share with other atoms. Generally speaking when non-metals steal
electrons from metals they form “ionic bonds”. When non-metals combine with other
non-metals they share their electrons to form “covalent bonds”.
The number of atoms they share electrons with depends on the number they need to
have a full octet.
Rules for Sharing or Stealing Electrons
1.
2.
3.
4.
5.
6.
Every atom must have a full outer orbital as a result of sharing or stealing
from other atoms. (8 for every atom except hydrogen).
Each “share” counts as two electrons (one from each atom).
Only VALENCE electrons (outer orbital) are counted.
If there are more than 3 atoms sharing, the atoms will attempt to spread as far
apart as possible.
Atoms can share up to 3 electrons, but the total in the outer orbital (including
those shared from the other atom) cannot exceed 8.
Hydrogen is considered a non-metal for our purposes.
Notice how Carbon has 4 valence electrons (group 4), and
therefore needs 4 more electrons. It borrows one from each
Chlorine.
Number of Bonds Possible:
Hydrogen
Sodium
Magnesium Boron
Carbon Nitrogen
Oxygen Fluorine Neon
Potassium Calcium
Aluminum Silicon Phosphorus Sulphur Chlorine Argon
Group 1
1.
2.
Decide if you are dealing with a metal and a non-metal OR two non-metals.
If you are dealing with a metal and a non-metal decide how many electrons are given away by
one atom and how many are taken by the other. Record each of these under the number of
bonds.
Example:
Na and Cl
Sodium must get rid of 1, Chlorine must gain 1.
Na = 1
3.
Cl = 1
If you are dealing with two non-metals, they must share. Figure out how many of each element
you will need to that if they share valence electrons they all end up with 8 in their octet.
Record how many bonds or shares each element must make.
Example: H and O
Hydrogen needs 1 (to fill outer orbital)
Oxygen needs 2 (to fill outer orbital)
H=1
O=2
Elements
Number of Bonds for each
Element
C (carbon)
C=
H (hydrogen)
H=
H (hydrogen)
H=
H (hydrogen)
Mg (magnesium)
Mg =
O (oxygen)
O=
Structure
Group 2
1.
2.
Decide if you are dealing with a metal and a non-metal OR two non-metals.
If you are dealing with a metal and a non-metal decide how many electrons are given away by
one atom and how many are taken by the other. Record each of these under the number of
bonds.
Example:
Na and Cl
Sodium must get rid of 1, Chlorine must gain 1.
Na = 1
3.
Cl = 1
If you are dealing with two non-metals, they must share. Figure out how many of each element
you will need to that if they share valence electrons they all end up with 8 in their octet.
Record how many bonds or shares each element must make.
Example: H and O
Hydrogen needs 1 (to fill outer orbital)
Oxygen needs 2 (to fill outer orbital)
H=1
O=2
Elements
Number of Bonds for each
Element
C (carbon)
C=
Cl (chlorine)
Cl =
O (oxygen)
O=
O (oxygen)
Mg (magnesium)
Mg =
F (fluoride)
F=
Structure
Group 3
1.
2.
Decide if you are dealing with a metal and a non-metal OR two non-metals.
If you are dealing with a metal and a non-metal decide how many electrons are given away by
one atom and how many are taken by the other. Record each of these under the number of
bonds.
Example:
Na and Cl
Sodium must get rid of 1, Chlorine must gain 1.
Na = 1
3.
Cl = 1
If you are dealing with two non-metals, they must share. Figure out how many of each element
you will need to that if they share valence electrons they all end up with 8 in their octet.
Record how many bonds or shares each element must make.
Example: H and O
Hydrogen needs 1 (to fill outer orbital)
Oxygen needs 2 (to fill outer orbital)
H=1
O=2
Elements
Number of Bonds for each
Element
C (carbon)
C=
O (oxygen)
O=
N (nitrogen)
H=
O (Oxygen)
Ne (neon)
Ne =
O=
O (oxygen)
Structure
Group 4
1.
2.
Decide if you are dealing with a metal and a non-metal OR two non-metals.
If you are dealing with a metal and a non-metal decide how many electrons are given away by
one atom and how many are taken by the other. Record each of these under the number of
bonds.
Example:
Na and Cl
Sodium must get rid of 1, Chlorine must gain 1.
Na = 1
3.
Cl = 1
If you are dealing with two non-metals, they must share. Figure out how many of each element
you will need to that if they share valence electrons they all end up with 8 in their octet.
Record how many bonds or shares each element must make.
Example: H and O
Hydrogen needs 1 (to fill outer orbital)
Oxygen needs 2 (to fill outer orbital)
H=1
O=2
Elements
Number of Bonds for each
Element
Si (silicon)
Si =
S (Sulphide)
S=
N (nitrogen)
N=
N (nitrogen)
K (potassium)
K=
N (nitrogen)
N=
Structure
Group 5
1.
2.
Decide if you are dealing with a metal and a non-metal OR two non-metals.
If you are dealing with a metal and a non-metal decide how many electrons are given away by
one atom and how many are taken by the other. Record each of these under the number of
bonds.
Example:
Na and Cl
Sodium must get rid of 1, Chlorine must gain 1.
Na = 1
3.
Cl = 1
If you are dealing with two non-metals, they must share. Figure out how many of each element
you will need to that if they share valence electrons they all end up with 8 in their octet.
Record how many bonds or shares each element must make.
Example: H and O
Hydrogen needs 1 (to fill outer orbital)
Oxygen needs 2 (to fill outer orbital)
H=1
O=2
Elements
Number of Bonds for each
Element
B (boron)
B=
O (oxygen)
O=
H (hydrogen)
H=
S (sulphide)
S=
Ar(argon)
Ar =
O (oxygen)
O=
Structure
Group 6
1.
2.
Decide if you are dealing with a metal and a non-metal OR two non-metals.
If you are dealing with a metal and a non-metal decide how many electrons are given away by
one atom and how many are taken by the other. Record each of these under the number of
bonds.
Example:
Na and Cl
Sodium must get rid of 1, Chlorine must gain 1.
Na = 1
3.
Cl = 1
If you are dealing with two non-metals, they must share. Figure out how many of each element
you will need to that if they share valence electrons they all end up with 8 in their octet.
Record how many bonds or shares each element must make.
Example: H and O
Hydrogen needs 1 (to fill outer orbital)
Oxygen needs 2 (to fill outer orbital)
H=1
O=2
Elements
Number of Bonds for each
Element
Na (sodium)
Na =
S (sulphur)
S=
S (sulphur)
S=
Oxygen (oxygen)
O=
Mg (magnesium)
Mg =
F (fluorine)
F=
Structure