Question

The vibrations of atoms and molecules produce electromagnetic radiation in the region of

• A. ultraviolet
• B. infrared
• C. visible light
• D. microwaves
• E. X-rays

Hint:

IR spectroscopy is a powerful tool for identifying functional groups based on their characteristic vibrational frequencies.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Electromagnetic (EM) radiation is produced by the acceleration of charged particles. Different types of EM radiation correspond to different energy ranges and are produced by different physical processes at the atomic and molecular level.
Step 2: Detailed Explanation:
Let's look at the origin of different regions of the EM spectrum:
- Microwaves: Primarily produced by the rotational motion of molecules and by man-made electronic devices like klystrons and magnetrons.
- Infrared (IR) Radiation: This radiation is directly associated with the thermal motion of atoms and molecules. When molecules vibrate or rotate, they can absorb or emit photons in the infrared range. Hence, IR is often called "heat radiation." The energy levels for molecular vibrations correspond to the infrared region.
- Visible and Ultraviolet (UV) Light: These are produced by electronic transitions in atoms and molecules. When an electron in an outer shell jumps to a lower energy level, it emits a photon. The energy of these photons typically falls in the visible or UV range.
- X-rays: These are higher-energy photons produced by two main mechanisms: transitions of electrons in the inner shells of heavy atoms, or the rapid deceleration of high-energy charged particles (like electrons hitting a metal target), a process known as bremsstrahlung.
The question specifically asks about the radiation from the vibrations of atoms and molecules. This process is the primary source of infrared radiation.
Step 3: Final Answer:
The vibrations of atoms and molecules produce electromagnetic radiation in the infrared region. This corresponds to option (B).