How does atomic weight affect entropy?

The relationship between atomic weight and entropy is connected to the concept of microstates and the configurational possibilities available to a system. Heavier atoms, due to their greater mass, typically have larger atomic volumes and can vibrate and form bonds in more diverse ways compared to lighter atoms. This increased diversity in the ways that heavier atoms can arrange themselves contributes to a greater number of accessible microstates, which directly correlates with higher entropy.

In thermodynamics, entropy is a measure of disorder and the number of ways in which a system can be arranged without changing its energy. Heavier atoms can contribute to more complex structures and have more vibrational modes compared to lighter ones. For example, consider a gas made from heavier atoms; at a given temperature, these atoms can occupy a greater phase space because they have more possible energy states and interactions. Consequently, the configurational entropy will be higher for that system made with heavier atoms than for one composed of lighter atoms.

This is why the option stating that heavier atoms have increased entropy accurately describes the relationship between atomic weight and entropy.