Write an expression for the energy of a single electron in a hydrogen-like orbit. Your expression should take into account a nuclear charge of Z and quantum number n. (b) Express your answer in Hartrees if the electron is in a hydrogen 1s orbital. (c) Calculate the energy in Hartrees of an electron in a helium 1s and a helium 2s orbital. (d) Neglecting the r12 term in the Hamiltonian, calculate in Hartrees the energy of helium excited state having one electron in a 1s orbital and the other electron in a 2s orbital.

For cyclohexane compounds drawn in a chair conformation:   -axial bonds are vertical  -equatorial bonds are parallel to two bonds within the ring.  thus, as i assume the chair conformation is drawn:   -the x group is in an axial position, as are the five other vertical bonds.  -three axial bonds are on the top face of the ring  -the other three axial bonds are on the bottom face  the position of the second substituent on each ring carbon is equatorial.  gauche groups must be on an adjacent carbon such as carbon 6 and carbon 2, and also gauche groups are rotated by 60 degrees relative to each other.  drawing the newman projections for c1–c2 and c1–c6 aids in visualizing the groups that are gauche to the y group on c1.  click this link and watch some academic videos that may you more understand the topic