How do you write the formula for ionic compounds?
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 has 2 valence electrons it readily gives away in order to seek the stability of the octet. This makes calcium a
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
Aluminum has an oxidation state of +3 or
Oxygen has an oxidation state of -2 or
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
I hope this is helpful.