Chemistry: A Molecular Approach (3rd Edition)

A photon is the smallest possible packet of electromagnetic radiation with energy equal to $hv$. Therefore, frequency is directly proportional to the energy of a photon and wavelength is inversely proportional to the energy of a photon.
The energy of a photon can be given by the following equations: $$E=hv$$ $$E=\frac{hc}{\lambda}$$