Quantized Energy
In 1900, Max Planck proposed that all energy is either released or absorbed in "chunks" of some minimum size. Just like you can only walk partway up a step, energy can only increase by a certain minimum factor. That factor is extremely small. Planck gave the name quantum (meaning "fixed amount") to the smallest quantity of energy that can be emitted or absorbed as electromagnetic radiation. He even came up with an equation that relates the energy to the radiation:
E = hν
where E is the energy of a photon, h is Planck's constant which is 6.63 x 10-34J s, and ν is the frequency.
According to Planck's theory, matter can emit energy only in factors of hν, like 2hν and 3hν and so forth. Since he difference between hv and 2hv is extremely small, we never notice the "steps" in real life. But, on the order of the atom, they are noticeable that energy is only in these chunks, or multiples of them.
The Photoelectric Effect
When you put aluminum in a microwave, it sparks. This is because the microwave photons produced by the microwave oven have the right amount of energy to kick valence electrons off the aluminum, which causes sparks or "lightning" to be emitted. Albert Einstein said that light is made of photons, or packets of energy. When these packets of light hit the electrons, they knock them loose, which causes sparks. Einstein deduced that each photon must have an energy equal to hv. This is aligned with Planck's theory, as well. |