Calculate the radius of first orbit of hydrogen atom and helium ion. Which one has smaller radius?give reason

Calculate the radius of first orbit of hydrogen atom and helium ion. W

1.	Calculate the radius of first orbit of hydrogen atom and helium ion. Which one has smaller radius?give reason
Answer» As the orbit is not a circle, there is no RADIUS. What you can calculate is the distance to the nucleus where the probability density to find the electron is highest, or you can calculate the expectation value for the distance.By accident, the most probable distance is very NEARLY the same as Bohr’s radius. Bohr ‘s value is 0.529 177 210 67(12) E-10 m.The expectation value is 1.5 times higher. But you can find the electron even at 5 times that distance with significant probability.For the He+ ion, you can just divide everything by Z = 2.