5 Steps to a 5 AP Chemistry 2019

CHAPTER

Spectroscopy, Light, and Electrons

IN THIS CHAPTER

Summary: In developing the model of the atom, it was thought initially that all sub-

atomic particles obeyed the laws of classical physics—that is, they were tiny bits of

matter behaving like macroscopic pieces of matter. Later, however, it was discovered

that this particle view of the atom could not explain many of the observations being

made. About this time, the dual particle/wave model of matter began to gain favor.

It was discovered that in many cases, especially when dealing with the behavior of

electrons, describing some of their behavior in terms of waves explained the obser-

vations much better. Thus, the quantum mechanical model of the atom was born.

Keywords and Equations

Speed of light, c = 3.0 × 108 ms-^1

E = energy n = frequency l = wavelength

p = momentum v = velocity n = principal quantum number

m = mass E = hn c = ln l=

h

mv

p = mv

E −×−

n

n= 2.178^10 joule

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2

Planck’s constant, h = 6.63 × 10 -^34 Js

The Nature of Light

Light is a part of the electromagnetic spectrum—radiant energy composed of gamma rays,

X-rays, ultraviolet light, visible light, etc. Figure 10.1 shows the electromagnetic spectrum.

10

KEY IDEA

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