Unit 3: Topic 11 - Spectroscopy and the Electromagnetic Spectrum

Question 1

What is electromagnetic radiation, and how does it relate to light?

Answer 1

• Electromagnetic radiation is defined as a form of radiant energy that exhibits wave-like behavior and travels through space at the speed of light in a vacuum.
• Light is a type of electromagnetic radiation and is carried in the form of photons.

Question 2

How can light be characterized?

Answer 2

• Light can act both as a particle(its photons) and as a wave(what it acts like most of the time). This is called a particle-wave duality.
• Light, in its wave-like form, oscillates back and forth periodically. The wavelength of light would then be the length of one period of the light wave. It can be calculated as the distance between two peaks in the wave, often measured in terms of nanometers.
• The frequency of light describes the number of waves that pass through a fixed place in a given amount of time and is measured in per-second(s^-1) or, more commonly, Hz(hertz).
• Frequency and wavelength have an inverse relationship as given by the equation C = Vλ, where c is the speed of light, v is the frequency in Hz, and λ is the wavelength in nanometers.
• Here is a visual representation.

Question 3

What is the electromagnetic spectrum?

Answer 3

• The electromagnetic spectrum classifies and arranges electromagnetic waves into sections according to their various wavelengths and frequencies.
• The visible spectrum, or light that we can see with our eyes, makes up a small portion of the different types of electromagnetic radiation that exist.
• Low energy light has long wavelengths and low frequencies(those on the right of the spectrum), and higher energy light has short wavelengths and high frequencies(those on the left of the spectrum).
• Here is the diagram for the electromagnetic spectrum.

Question 4

What is spectroscopy, and what are the different types of electromagnetic radiation?

Answer 4

• Spectroscopy is when you apply different types of radiation to atoms and molecules; the energy of light absorbed or emitted can tell you about the matter the light interacted with.
• Ultraviolet/Visible radiation causes transitions of electrons from one energy level to another through electron excitation. It gives you information about atomic structure and electron energy levels.
• Infrared radiation causes transitions in molecular vibrational levels. It gives you information about bonds and their bond order(for example, double bonds have a bond order of two).
• Microwave radiation causes transitions in molecular rotational levels. It gives information about the polarity of bonds.