Problem 1
Explanation of equation 11.12 in Atkins
11.12) .5mv2 = hν – Φ
This equation is very similar to the equation for total energy: E = KE + PE. KE is defined as .5mv2 so if we want to solve for KE we must rearrange the equation:
KE = E – PE
The total energy is the energy that is supplied by the photon, so E = hν. The work function, Φ, is equivalent to the potential energy of the electron. So what the equation is really saying is that the photon, with an energy hf, must supply enough energy to the electron to overcome its potential energy, phi. This potential energy is in the form of electrostatic energy between the electron and the nucleus. Any remaining energy is converted to kinetic energy, which gives the velocity of the ejected electron.