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The Elements & their Properties
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The Elements & their Properties
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A D V E R T I S E M E N T
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Elements and Their Properties
Radiant Energy
To some extent, the properties of electrons can be compared with the properties of a closely related phenomenon, radiant energy or light.
(more content follows the advertisement below) A D V E R T I S E M E N T
Radiant energy, also known as electromagnetic radiation, travels through a vacuum in waves at a constant speed of 3.0 X 108 m/sec.
In many ways the waves of electromagnetic radiation are like waves in water. You have probably seen closely spaced, choppy waves on a small lake. You may also have seen, on larger bodies of water like the ocean, waves that are farther apart. The difference between these two types of waves is in their wavelength (lambda), which is the distance from crest to crest.
A wave can also be characterized by its frequency - that is, the number of wave crests that pass a given point in a unit time. The frequency (nu) of a wave is related to its wavelength by the equation
C = ^ * f
where c is the constant speed of light, 3.0 X 108 m/sec. From this equation you can see that as wavelength increases, the frequency of the wave decreases. The energy associated with a wave is directly proportional to its frequency. Hence, the higher the frequency, the shorter the wavelength and the higher the energy of the wave.
Figure (next page) shows the wide range of electromagnetic radiation from AM radio waves with a wavelength of 104 m to gamma waves with a wavelength of 10 -12 m. This range is called the electromagnetic spectrum. The common names of the other kinds of electromagnetic radiation and their wavelengths are also given. Notice that visible light, electromagnetic radiation with wavelengths between 4 X 10 -7 and 7 X 10 -7 m, comprises only one small part of the electromagnetic spectrum. In Figure 5.2 you can see that red light has a longer wavelength than blue light. Red light, then, has a lower frequency and is associated with less energy than blue light. Infrared light, microwaves, television waves, and radio waves are invisible forms of electromagnetic radiation; their wavelengths are greater than that of visible light, and thus their energies are lower than that of visible light.
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