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A topic from the subject of Contributions of Famous Chemists in Chemistry.

  • 11 months ago
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The Discovery and Application of X-Ray Crystallography by Sir William Henry Bragg
Introduction

X-ray crystallography is a technique that uses X-rays to determine the structure of crystals. It was discovered by Sir William Henry Bragg in 1912. X-ray crystallography has revolutionized chemistry by providing a way to determine the structure of molecules and crystals. This information has been used to develop new materials, drugs, and treatments for diseases.


Basic Concepts

X-rays are a type of electromagnetic radiation. They have a wavelength that is shorter than visible light, but longer than gamma rays. When X-rays interact with matter, they can be scattered or absorbed. The scattering of X-rays by crystals is used to determine the structure of the crystal.


Crystals are materials that have a repeating arrangement of atoms or molecules. The arrangement of atoms or molecules in a crystal is called the crystal structure. The crystal structure can be determined by measuring the scattering of X-rays by the crystal.


Equipment and Techniques

The equipment used for X-ray crystallography is an X-ray diffractometer. An X-ray diffractometer consists of an X-ray source, a sample holder, and a detector. The X-ray source emits X-rays, which are then directed at the sample. The sample holder holds the crystal in place. The detector measures the intensity of the X-rays that are scattered by the crystal.


Several different techniques can be used to measure the scattering of X-rays by a crystal. The most common technique is the powder diffraction method. In the powder diffraction method, a powdered sample of the crystal is used. The powder diffraction method is used to determine the average structure of the crystal.


Types of Experiments

There are several different types of X-ray crystallography experiments. The most common type of experiment is the single-crystal experiment. In a single-crystal experiment, a single crystal of the material is used. The single-crystal experiment is used to determine the detailed structure of the crystal.


Other types of X-ray crystallography experiments include the powder diffraction experiment and the fiber diffraction experiment. The powder diffraction experiment is used to determine the average structure of a material. The fiber diffraction experiment is used to determine the structure of a material that is in the form of a fiber.


Data Analysis

The data from an X-ray crystallography experiment is analyzed to determine the structure of the crystal. The data is analyzed using a computer program. The computer program uses the data to calculate the electron density of the crystal. The electron density of the crystal is a map of the electrons in the crystal. The electron density map can be used to determine the positions of the atoms and molecules in the crystal.


Applications

X-ray crystallography has a wide range of applications in chemistry. Some of the applications of X-ray crystallography include:



  • Determining the structure of proteins
  • Determining the structure of DNA
  • Determining the structure of drugs
  • Developing new materials

Conclusion

X-ray crystallography is a powerful technique that has revolutionized chemistry. X-ray crystallography has provided a way to determine the structure of molecules and crystals. This information has been used to develop new materials, drugs, and treatments for diseases.


The Discovery and Application of X-Ray Crystallography by Sir William Henry Bragg
Introduction
X-ray crystallography, a groundbreaking technique developed by Sir William Henry Bragg, revolutionized the study of crystal structures in chemistry.
Discovery
In 1912, Bragg and his son, Lawrence Bragg, discovered that X-rays diffract (bend) when passing through crystals. This diffraction pattern provides information about the arrangement of atoms within the crystal.
Bragg's Law
Bragg's Law, proposed by Bragg and his son, describes the conditions for X-ray diffraction:

nλ = 2d sin θ


where:
- n is an integer (order of diffraction)
- λ is the X-ray wavelength
- d is the interplanar distance in the crystal
- θ is the diffraction angle
Application in Chemistry
X-ray crystallography allows the determination of:
- Crystal structures
- Interatomic distances and bond angles
- Molecular shapes
- Unit cell parameters
- Crystallographic planes
Impact
The discovery of X-ray crystallography enabled:
- Understanding of crystal structures in materials science
- Advancement of the fields of mineralogy, biology, and medicine
- Development of new materials and pharmaceuticals
Recognition
Sir William Henry Bragg and his son received the Nobel Prize in Physics in 1915 for their pioneering work in X-ray crystallography.
Conclusion
The discovery and application of X-ray crystallography by Sir William Henry Bragg revolutionized chemistry, providing invaluable insights into the structure and properties of materials at the atomic level.
Experiment: The Discovery and Application of X-Ray Crystallography by Sir William Henry Bragg
Introduction
This experiment demonstrates the use of X-ray crystallography, a technique developed by Sir William Henry Bragg in the early 1900s. X-ray crystallography allows scientists to determine the atomic and molecular structure of crystals by analyzing the patterns produced when X-rays pass through the crystal.
Materials
X-ray source Crystal sample
Detector (e.g., film or digital camera) Ruler or caliper
* Calculator
Procedure
1. Place the crystal sample in the path of the X-ray beam.
2. Position the detector so that it is perpendicular to the X-ray beam.
3. Expose the crystal to the X-ray beam for a period of time.
4. Develop the film or image captured by the digital camera.
Observations
The X-ray diffraction pattern will consist of a series of concentric circles or spots. The radius of each circle or the distance between the spots is related to the wavelength of the X-rays and the spacing between the atoms in the crystal.
Analysis
Using the Bragg equation, the spacing between the atomic planes in the crystal can be calculated. This information can then be used to determine the crystal structure.
Significance
X-ray crystallography is a powerful tool that has been used to determine the structure of a wide variety of materials, including proteins, DNA, and minerals. This information has been used to advance our understanding of the fundamental building blocks of matter and to develop new materials with improved properties.

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