1. The problem statement, all variables and given/known data Calculate the avg. distance from the Hydrogen nucleus for an electron in 2p. 2. Relevant equations <r> = int[r^3 |R|^2]dr from 0->infinity For Hydrogen 2p, R = (1/a)^3/2 (1/(2*sqrt(sigma))*sigma*exp(-sigma/2) where sigma = r/a 3. The attempt at a solution I get 1/4a^4 (24 a^5) = 6a but the answer's supposed to be 5a. (5a for 2p is supposed to be less than 6a, which is the avg distance for 2s.) What am I doing wrong??????