In the scope of its subject, chemistry occupies an intermediate position between physics and biology.[6] It is sometimes called the central science because it provides a foundation for understanding both basic and applied scientific disciplines at a fundamental level.[7] For example, chemistry explains aspects of plant growth (botany), the formation of igneous rocks (geology), how atmospheric ozone is formed and how environmental pollutants are degraded (ecology), the properties of the soil on the Moon (cosmochemistry), how medications work (pharmacology), and how to collect DNA evidence at a crime scene (forensics).
Chemistry has existed under various names since ancient times.[8] It has evolved, and now chemistry encompasses various areas of specialisation, or subdisciplines, that continue to increase in number and interrelate to create further interdisciplinary fields of study. The applications of various fields of chemistry are used frequently for economic purposes in the chemical industry.
is the analysis of material samples to gain an understanding of their chemical composition and structure. Analytical chemistry incorporates standardized experimental methods in chemistry. These methods may be used in all subdisciplines of chemistry, excluding purely theoretical chemistry.[74]
In analytical chemistry, spectroscopy studies interactions between electromagnetic radiation (light) and matter.[75] A spectrophotometer is a machine used to measure the effect light has on matter. The model pictured is the Beckman DU-640
is the study of the properties and reactions of inorganic compounds, such as metals and minerals.[77] The distinction between organic and inorganic disciplines is not absolute and there is much overlap, most importantly in the sub-discipline of organometallic chemistry.
The Kaminsky catalyst is an organometallic complex that features either zirconium or hafnium metal centers. Depending on the placement of the catalyst's cyclopentadieneligands, it can produce polypropylenes with different tacticity.[78]1 creates atactic polypropylene, which is soft and amorphous with a free-flowing composition. 2 creates isotactic polypropylene, which is hard and used in re-usable plastic containers. 3 creates syndiotactic polypropylene, which is rubbery and semi-crystalline.[79]
Inorganic chemistry
is the preparation, characterization, and understanding of solid state components or devices with a useful current or future function.[80] The field is a new breadth of study in graduate programs, and it integrates elements from all classical areas of chemistry like organic chemistry, inorganic chemistry, and crystallography with a focus on fundamental issues that are unique to materials. Primary systems of study include the chemistry of condensed phases (solids, liquids, polymers) and interfaces between different phases.
Materials chemistry
is the study of neurochemicals; including transmitters, peptides, proteins, lipids, sugars, and nucleic acids; their interactions, and the roles they play in forming, maintaining, and modifying the nervous system.
Neurochemistry
is the study of how subatomic particles come together and make nuclei. Modern transmutation is a large component of nuclear chemistry, and the table of nuclides is an important result and tool for this field. In addition to medical applications, nuclear chemistry encompasses nuclear engineering which explores the topic of using nuclear power sources for generating energy[81][82]
The Little Boy is an atomic bomb utilizing a uranium-235fission reaction.[83] By firing sub-critical uranium into another mass of sub-critical uranium within the bomb, a self-sustaining nuclear reaction (the critical mass). It generated an explosive force of over 15,000 tons of equivalent TNT
Nuclear chemistry
is the study of the structure, properties, composition, mechanisms, and reactions of organic compounds. An organic compound is defined as any compound based on a carbon skeleton. Organic compounds can be classified, organized and understood in reactions by their functional groups, unit atoms or molecules that show characteristic chemical properties in a compound.[84]
