Question

Recall that the color of neon lights is dependent on the type of gas that is in

the sign. Helium gas produces yellow light, neon gas produces red light, and argon gas
produces blue light. Explain what is happening to the electrons of the gas atoms in these
signs and why each gas produces different light. Which electrons have the most energy?

Answer 1

When an electron is energised, it has the ability to move to a higher energy level and on its fall, release a photon which is a packet of light with a specific frequency that corresponds to the distance that the electron fell.
A neon atom has two outer valence shells, whereas an argon atom has three outer valence shells. An electron falling from the third valence shell would have more kinetic energy than one that drops from the second valence shell, therefore, the photon released from an electron in the argon atom would have higher energy, and a higher frequency. That’s why a neon atom releases red light (~635 nm) and an argon atom releases blue light (~450 nm) which has a higher frequency than red wavelengths.