# Homework Help: How much energy is required to ionize the hydrogen atom

1. Aug 11, 2008

### Laxman2974

1. The problem statement, all variables and given/known data
(a)the electric potential established by the nucleus of a hydrogen atom at the average distance of the circulating electron (r = 5.29 multiplied by 10-11 m)
I solved this part using V = kq/r and got 27.2249V

(b) the electric potential energy of the atom when the electron is at this radius, and

I thought this was a simple as converting to electron volts but it's not? What is next? This is where I am stuck.

(c)the kinetic energy of the electron, assuming it to be moving in a circular orbit of this radius centered on the nucleus.

(d) How much energy is required to ionize the hydrogen atom (that is, to remove the electron from the nucleus so that the separation is effectively infinite)?

2. Aug 11, 2008

### Laxman2974

So what is the difference between finding the electric potential of the nucleus and of the atom? any help here?

3. Aug 11, 2008

### Gear300

Part (a) asks for electric potential. Part (b) asks for electric potential energy. When you have a system of 2 charges, which you can assume this to be, the electric potential energy is given by U = k*q1*q2/r, and it is the energy of the system, meaning it is the energy of q1 in respect to q2 as well as q2 in respect to q1. U = qV, so technically, for part (b), you simply have to multiply the answer in part (a) by the charge of the electron. If you want to give the value in electron-volts, then simply divide your answer by the magnitude of charge for a proton or electron.