how does the massof an atom affect the rate it diffuses
2 answers
http://www.chem.tamu.edu/class/majors/tutorialnotefiles/graham.htm
I assume that you are talking about diffusion in a gas.
Smaller atoms and molecules diffuse faster. There is a number called the diffusion coefficient, D, that characterizes how fast a molecule diffuses in a gas from regions of high concentration to lower ccncentration. D is roughly equal to the product of the molecular speed and the average distance between collisions (which is called the mean free path). Both speed and the mean free path are larger for smaller molecules, and that is why the diffusion coefficient is larger for less massive atoms and molecules.
Smaller atoms and molecules diffuse faster. There is a number called the diffusion coefficient, D, that characterizes how fast a molecule diffuses in a gas from regions of high concentration to lower ccncentration. D is roughly equal to the product of the molecular speed and the average distance between collisions (which is called the mean free path). Both speed and the mean free path are larger for smaller molecules, and that is why the diffusion coefficient is larger for less massive atoms and molecules.