1 Consider the first atom of each part of the molecule. An atom with higher atomic number has higher priority. (e.g. I > Cl > C > H)  If the first atom of two groups is the same, consider the second atom(s) in the same way as the first. (e.g. -C(CH3)3 > -CH(CH3)2 > -CH2CH3 > -CH3).
1 You can also use a toilet plunger on your bathroom sink. 2  Fill up the sink with water first, the use the plunger vigorously on the drain just as you would a toilet. 3  This will lift and agitate any blockage in the drain. It will smell a bit like vinegar for about a day. 2  You can also use a toilet plunger on your bathroom sink. 3  Fill up the sink with water first, the use the plunger vigorously on the drain just as you would a toilet.
Soap scum, hair and other debris can easily block a bathtub drain, and the blockage tends to grow as the water flows more slowly and allows more sediment to settle. If you don't know where the blockage is, the tub drain is usually a good place to start looking for it, but not if sink water is backing up into the tub.