Dr. Subhash C. Goel
South GA College
Douglas, GA
Electronic
Structure of Atoms
A wave is a continuously repeating change or oscillation in matter or in a physical field.
Light is an electromagnetic wave, consisting of oscillations in electric and magnetic fields traveling through space.
A wave can be characterized by its wavelength and frequency.
Wavelength, symbolized by the Greek letter lambda, , is the distance between any two identical points on adjacent waves.
Frequency, symbolized by the Greek letter nu, , is the number of wavelengths that pass a fixed point in one unit of time (usually a second). The unit is 1/S or s-1, which is also called the Hertz (Hz).
Wavelength and frequency are related by the wave speed. The speed of light, c, is 3.00 x 108 m/s. c =
The relationship between wavelength and frequency due to the constant velocity of light is illustrated on the next slide.
The Nature of Energy
The wave nature of light does not explain how an object can glow when its temperature increases. Also, The wave theory could not explain the photoelectric effect.
The Nature of Energy
• Therefore, if one knows the wavelength of light, one can calculate the energy in one photon, or packet, of that light: c =
E = h
In the early 1900s, the atom was understood to consist of a positive nucleus around which electrons move (Rutherford’s model).
This explanation left a theoretical dilemma:
According to the physics of the time, an electrically charged particle circling a center would continually lose energy as electromagnetic radiation. But this is not the case—atoms are stable.
