Stellar Photons are packets of electromagnetic energy. Each photon has a specific amount of energy that depends on its frequency or wavelength, according to the equation . This means that as frequency increases, photon energy increases, and as wavelength increases, photon energy decreases. Because of this inverse relationship, high-energy light has short wavelengths, while low-energy light has long wavelengths.
In chemistry, photon properties are important because atoms and molecules interact with specific amounts of energy. A photon can be absorbed only if its energy matches the energy difference between two allowed states. That is why different parts of the electromagnetic spectrum cause different kinds of changes. Lower-energy photons may cause rotational or vibrational changes, while higher-energy photons can promote electrons between energy levels or even ionize them. So the key idea is that photon energy controls what kind of change can happen in matter.