Based upon Max Planck's theory of black-body radiation, Einstein theorized that the energy in each quantum of light was equal to the frequency multiplied by a constant, later called Planck's constant. A photon above a threshold frequency has the required energy to eject a single electron, creating the observed effect.
According to Max Planck light energy is quantized and is released or absorbed as an integer multiple of a small packet of energy which he called a photon. Therefore the energy stored in a photon of light is given by the equation,
E = hV
where E is the energy of the photon, v is the frequency of light and h is the Planck’s constant.
Einstein used the concept of light behaves as photons, discrete energy packets instead of waves to explain the photoelectric effect.
He realized that the physical and chemical properties of elements<span> were related to their atomic mass in a '</span>periodic<span>' way, and </span>arranged<span> them so that groups of </span>elements<span> with similar properties fell into vertical columns in </span>his table<span>. </span><span> </span>