Why does the heat capacity decreases as atomic mass increases?

The general trend for a substance's heat capacity and atomic mass is that they are inversely proportional. This is because denser or larger atoms have particles that are closer to each other. The close proximity of these particles make it easier to transfer heat because of their increased vibration, making the heat capacity required smaller. 

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .