In a compound, such as ch3oh, how determine which is the central atom?

Choose the least electronegative atom other than H.

Explanation:

A Lewis structure consists of terminal atoms and one or more central atoms.

H can be only a terminal atom because it can form only one bond.

So the central atom must be either C or O.

The central atom is the less electronegative atom: C.

So, start the Lewis structure with a central C atom.

Then attach an O atom to get C-O.

Finally, attach the H atoms.

The condensed formula often gives you a clue where they go.

The formula CH₃OH implies that there are 3 H atoms on C and one on O.

The connectivity of the atoms is then as in the diagram below.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"