Chemistry

Determining a Molecular Formula from a Diagram:
 
Molecules are sometimes represented as “ball and stick” models.
 
In all of these representations, carbon atoms are black or gray; hydrogen atoms are white; oxygen atoms are red, and nitrogen atoms are blue. Those atoms are the ones that we will most commonly encounter. But sometimes, there will be other atoms. For example, in this problem set, sulfur is shown in yellow, and phosphorous is shown in orange.
 
Here are two molecules that are similar in structure. The molecule on the left has the molecular formula C₂H₅NO. The molecule on the right is similar, but the red sphere for oxygen is replaced by a yellow sphere for sulfur; thus, its molecular formula is C₂H₅NS.
 
 
Determine the molecular formulas for the four molecules shown below.
 

3. The yellow sphere is sulfur.

4. The orange sphere is phosphorous.