How do you write chemical formulas based on chemical names?
1. Mg2C ==> First, just write down the metal and nonmetal (MgC). Now, find out the charges. Based on the periodic table, Mg has a charge of +2 and Carbon has a charge of -4. To write chemical formulas, switch the charges to form subscripts. So since Mg has a charge of +2, C will have a subscript of 2. Since C has a charge of -4, Mg will have a charge of 4. Now you have Mg4C2. However, you can reduce the ratio of the subscripts to be Mg2C. 2. AlCl3 • 6H2O ==> First, just deal with the ionic compound. Then worry about the hydrate. So, for the ionic compound, switch charges to form subscripts. Since Al has a charge of +3, Cl has a subscript of 3. Since Cl has a charge of -1, Al has a subscript of 1. Therefore, you get AlCl3. Now, for the hydrate, you add it on with a dot. Since hexa means 6, there’s 6H2O. Thus, you get AlCl3 • 6H2O. 3. H2CO3 ==> Since “carbonic” has an “ic” ending, it contains the polyatomic “carbonate” with an “ate” ending. Remember that the suffix “ate” changes to “ic”
