Electronic Structure of Atoms. Wave Nature of Light section 6.1 . Much of what we know about electrons in atoms came from analyzing light that is emitted or absorbed by substances, so it figures that to understand electrons better, understanding light better would help.
The color and intensity of the light emitted by a hot object depend on the temperature of the object. The temperature is highest at the center of this pour of molten steel. As a result, the light emitted from the center is most intense and of shortest wavelength.
When photons of sufficiently high energy strike a metal surface, electrons are emitted from the metal
The photoelectric effect is the basis of the photocell shown in (b). The emitted electrons are drawn toward the positive terminal. As a result, current flows in the circuit. Photocells are used in photographic light meters as well as in numerous other electronic devices.
E = −RH
ni2The energy absorbed or emitted from the process of electron promotion or demotion can be calculated by the equation:
where RH is the Rydberg constant, 2.18 10−18 J, and ni and nf are the initial and final energy levels of the electron.