The Foundations of Chemistry

Sir Isaac Newton, one of the giants of science. You probably know of him from his theory of

gravitation. In addition, he made enormous contributions to the understanding of many

other aspects of physics, including the nature and behavior of light, optics, and the laws of

motion. He is credited with the discoveries of differential calculus and of expansions into

infinite series.

5-1 0Electromagnetic Radiation 195

Figure 5-12 (a) Dispersion of visible light by a prism. Light from a source of white light

is passed through a slit and then through a prism. It is spread into a continuous spectrum

of all wavelengths of visible light. (b) Visible light is only a very small portion of the

electromagnetic spectrum. Some radiant energy has longer or shorter wavelengths than our

eyes can detect. The upper part shows the approximate ranges of the electromagnetic

spectrum on a logarithmic scale. The lower part shows the visible region on an expanded

scale. Note that wavelength increases as frequency decreases.

4000 5000 6000 7000

7.50 × 1014 6.00 × 1014 5.00 × 1014 4.28 × 1014

λ(Å)

v(Hz)

White

light

Prism

Increasing

wavelength

Gamma rays

X-rays

Ultraviolet

rays

Infrared rays

(heat)

Microwaves

Hertzian waves

(radio, TV)

λ(Å)

v(Hz)

10 –3 10 –1 10 103 105 107 109 1011

3 × 1019 3 × 1015 3 × 1011 3 × 107

Low energy

Low frequency

Long wavelength

High energy

High frequency

Short wavelength

Visible light

(a)

(b)