Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
42 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER
5
2. What is the wavelength of X rays having a frequency of
4.80 ϫ 10 17 Hz?
3. An FM radio station broadcasts at a frequency of 98.5 MHz.
What is the wavelength of the station’s broadcast signal?
Particle nature of light One of the first major clues to the electron structure of atoms was Albert Einstein’s explanation of the
photoelectric effect, a phenomenon in which electrons are ejected
from the surface of a polished metal plate when it is struck by light.
Whether or not electrons are ejected depends on the frequency
(color) of the incident light. In 1905, Einstein reasoned that this phenomenon could be explained only if light could act like a stream of
particles that knocked electrons out of atoms. Particles, or photons,
of light at the high-frequency (violet) end of the visible spectrum
had greater energy and were therefore more effective at dislodging
electrons.
The energy of a photon (E photon ) of a certain frequency () can
be calculated by using the following equation in which h represents
Planck’s constant (h ϭ 6.626 ϫ 10 Ϫ34 J и s).
E photon ϭ h
Practice Problems
4. Calculate the energy of a gamma ray photon whose frequency
is 5.02 ϫ 10 20 Hz.
5. What is the difference in energy between a photon of violet
light with a frequency of 6.8 ϫ 10 14 Hz and a photon of
red light with a frequency of 4.3 ϫ 10 14 Hz?
6. Calculate the energy of a photon of ultraviolet light that has a
wavelength of 49.0 nm.
Atomic emission spectra When atoms of an element in the
gaseous phase are excited by an input of energy, such as that from a
high-voltage electrical source, they emit light. (A neon sign works
on this principle.) This emitted light can be broken into a spectrum
consisting of discrete lines of specific frequencies, or colors. This
pattern of frequencies (colors) is unique to each element and is
known as the element’s atomic emission spectrum.
Consider the fact that each discrete frequency consists of
▲
▲
42 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER
5
2. What is the wavelength of X rays having a frequency of
4.80 ϫ 10 17 Hz?
3. An FM radio station broadcasts at a frequency of 98.5 MHz.
What is the wavelength of the station’s broadcast signal?
Particle nature of light One of the first major clues to the electron structure of atoms was Albert Einstein’s explanation of the
photoelectric effect, a phenomenon in which electrons are ejected
from the surface of a polished metal plate when it is struck by light.
Whether or not electrons are ejected depends on the frequency
(color) of the incident light. In 1905, Einstein reasoned that this phenomenon could be explained only if light could act like a stream of
particles that knocked electrons out of atoms. Particles, or photons,
of light at the high-frequency (violet) end of the visible spectrum
had greater energy and were therefore more effective at dislodging
electrons.
The energy of a photon (E photon ) of a certain frequency () can
be calculated by using the following equation in which h represents
Planck’s constant (h ϭ 6.626 ϫ 10 Ϫ34 J и s).
E photon ϭ h
Practice Problems
4. Calculate the energy of a gamma ray photon whose frequency
is 5.02 ϫ 10 20 Hz.
5. What is the difference in energy between a photon of violet
light with a frequency of 6.8 ϫ 10 14 Hz and a photon of
red light with a frequency of 4.3 ϫ 10 14 Hz?
6. Calculate the energy of a photon of ultraviolet light that has a
wavelength of 49.0 nm.
Atomic emission spectra When atoms of an element in the
gaseous phase are excited by an input of energy, such as that from a
high-voltage electrical source, they emit light. (A neon sign works
on this principle.) This emitted light can be broken into a spectrum
consisting of discrete lines of specific frequencies, or colors. This
pattern of frequencies (colors) is unique to each element and is
known as the element’s atomic emission spectrum.
Consider the fact that each discrete frequency consists of
▲
▲