I’m not sure how to take the chemical name and change it into the chemical formula. I don’t know how convalent and ionic bonding add into the mix, and the periodic table really confuses me!
Here’s a couple examples:
1.magnesium carbide
2.aluminum chloride hexahydrate
3.carbonic acid
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” and the suffix “ite” changes to “ous.” So, back to the problem, since carbonate has a charge of -2, H has a subscript of 2. And since H has a charge of 1, CO3 has a subscript of 1. So, we get H2CO3.
Hope this helps!
Yes, I understand your confusion, it is important to know the difference between covalent compounds (when two non-metal reacts, these are the elements to the right side of the periodic table), and ionic compounds (when a non-metal combines with a metal). There are different rules and conventions for the different types of compounds. Also, you’ll need to be familiar with the different ions and their charges. (metal typically forms cations (+ charges), and nonmetal are generally anions (- charges). Unfortunately as previous answer indicated, these are just things you have to know (like the vocabulary words and grammar rules in learning a new language, there is no easy shortcut on this one)
Based on your examples #1 is an ionic compound and #2 is a ionic compound but a hydrate (just add 6 H2O at the end), but you’ll need to know the charge on the Aluminum ion (typically 3+) in order to know how many chlorides (Cl-) to combine with aluminum. #3 is a acid and that’s a completely different set to rules. It will be useful if you know the polyatomic anions (i.e. carbonate ion = CO3 2-, and this is of course part of carbonic acid (H2CO3)
Unfortunately the only solution is just to remember, because there is no way you can derive the chemical formula from name if you do not know the various terms (like carbide, sulfite, nitrate, nitrite etc) but if you are still a student then the exams will give you the formulae for the more difficult chemicals. Though of couse some can be derived easily, for instance Phosphorus pentachloride, penta = 5, P is phosphorus, chloride is Cl, so you get PCl5! But others like cyclotrimethylene trinitramine or dinitro-diphenyl-trichloroethane takes a lot of figuring out to do. Cheerio.
Its very easy to write chemical formulas based on chemical names for ex:- Kmno4
here K = pottassium
(Mno4)-2= manganate ion
therefore the chemical name for Kmno4 is pottassium permanganate
Here’s a good website:http://www.woodrow.org/teachers/chemistr…
if you follow the rules, you should get it. good luck!! ;]