Read the problem carefully and identify the location of its element in periodic table.
Combine the cation and anion to form an electrically neutral compound.
Write the formulas for ionic compounds of an aluminum cation and each of the following anions.
An aluminum cation is predicted to have a charge of +3 because Al is a metal in Group 3A.
The ionic formula are listed below.
AlF3, Al2S3, Al(NO3)2
The ionic compound used in some sidewalk de-icers is made from calcium and chlorine. What formula would represent that compound?
Calcium belongs to Group IIA, it will form ions with a charge of +2. Chlorine is in Group VIIA and so will tend to form ions with a charge of -1.
To form an electrically neutral ionic compound, there must be two chloride ions for every calcium ion. Therefore the formula will be CaCl2.
The ionic formula for the compound is CaCl2.