# Thread: How do you find the molecular formula of a certain substance?

1. ## How do you find the molecular formula of a certain substance? var addthis_config = {"data_track_clickback":false};

For example Magnesium Chloride or MgCl2, how do i find out that there is one Magnesium atom and 2 chlorine atoms?
for example magnesium chloride or mgcl2. how do i find the 2 chlorine atoms and can you please show me steps how to do it because how does +2 atom go with 2, -1 atoms to make Mgcl2

2. atomic absorbtion spectroscopy will give how much metals u have. testing for metals is done daily in labs all over the world

3. In the Periodic Table, under the top right number to the right, it will list the various charges possible for each atom:
For instance, Calcium has only one number , which is +2
Arsenic has four possible charges, which are + or - 3 and + or - 5
Mg has a charge of +2 and Chlorine has charges of either + or - 1, 3, 5, 7
One Magnesium atom (witha positive charge of 2) will combine will two Chlorine Atoms with a charge of -1

4. Molecular formulas are easy in your case. Future molecular formula is a process of finding the formula through a reaction and the mass of the products/reactants. In your case, it's nomenclature. I have just what you need for that. With MgCl2, you just need to look at the periodic table. We can assume that The column with Li is 1+ charge due to a loss of a valence electron. Mg is 2+. We skip across the transition metals because they change around. The Boron column (B) is -5 charge. C is -4. N -3, O -2, F -1 and the noble gases being 0 usually. Cl is in the column of F. It's a -1 charge. Mg is 2+ being in the second column. We have to get the elements to 0 charge. MgCl2. Now.. Potassium Sulfide. K is 1+ charge. Sulfur is -2. So naturally, it makes K2S. Now, column 1 is ALWAYS 1+ and column 2 is ALWAYS 2+. The non-metals we "assume" are
-5,-4,-3,-2,-1, and 0; these are just usually the case. Bismuth (Bi) likes to be a 5+ for instance. If you want to know how to do this, just use the "Nomenclature Flowchart" right here: http://www.sciencewoods.com/tools.html It's quite helpful.

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts