What do valence electrons have to do with bonding?
These electrons are found in the s and p orbitals of the highest energy level for the element.
Sodium has 1 valence electron from the 3s orbital
Phosphorus has 5 valence electrons 2 from the 3s and 3 from the 3p
Lets take the ionic formula for Calcium Chloride is
Calcium is an Alkaline Earth Metal in the second column of the periodic table. This means that calcium
Chlorine is a Halogen in the 17th column or
Chlorine has 7 valence electrons. It needs one electron to make it stable at 8 electrons in its valence shells. This makes chlorine a
Ionic bonds form when the charges between the metal cation and non-metal anion are equal and opposite. This means that two
This makes the formula for calcium chloride,
For the example Aluminum Oxide
The common multiple of 2 and 3 is 6.
We will need 2 aluminum atoms to get a +6 charge and 3 oxygen atoms to get a -6 charge. When the charges are equal and opposite the atoms will bond as
In molecular (covalent) compounds these same valence electrons are shared by atoms in order to satisfy the rule of octet.
I hope this is helpful.