X-ray
Definition and meaning of X-ray in chemistry.
An X-ray is a form of high-energy electromagnetic radiation with a wavelength ranging from about 0.01 to 10 nanometers. In chemistry, X-rays are widely used to determine the atomic and molecular structure of crystals and to identify elemental composition.
In more detail
Because X-ray wavelengths are on the same order of magnitude as the spacing between atoms in a crystal lattice, they undergo diffraction when passing through crystalline materials. This phenomenon, known as X-ray crystallography, allows chemists to map the electron density of a sample and deduce the precise three-dimensional arrangement of atoms in molecules, ranging from simple salts to complex proteins. Additionally, techniques like X-ray fluorescence are used to determine the elemental composition of materials by analyzing the secondary X-rays emitted when a sample is bombarded with high-energy radiation.
Key facts
| Field | Analytical Chemistry |
|---|---|
| Wavelength Range | 0.01 to 10 nm |
| Key Application | X-ray crystallography |
Rosalind Franklin used X-ray diffraction to capture an image known as Photo 51, which provided crucial evidence for the double-helix structure of DNA.
Frequently asked questions
How does X-ray crystallography work?
It works by shining a beam of X-rays at a crystal, which scatters the rays into a specific diffraction pattern that can be analyzed to determine the exact arrangement of atoms.