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ChemistryChemistry is the study of structure, properties, composition, and transformation of substances. Chemistry deals with chemical elements and compounds, which consist of atoms and molecules, and the reactions between them. See also: the periodic table and list of compounds. Table of contents showTocToggle("show","hide") 1 Overview 2 Branches of chemistry 3 Chemicals and interactions 4 Quantitative chemistry 5 States of matter 6 Acids and bases 7 Kinetics and thermodynamics 8 History of chemistry 9 Etymology 10 See also 11 External links Overview The atomic theory is basic to chemistry. The theory states that all matter is composed of a set of very small units called atoms. One of the very first laws to be discovered leading to the establishment of chemistry as a science is the Law of Conservation of Mass. This law states there is no detectable change in the quantity of matter during an ordinary chemical reaction. (Modern physics now shows that it is actually energy that is conserved, and that energy and mass are related) On a superficial level this means that if we start off with 10,000 atoms and proceed with many chemical reactions, we will still be left with exactly 10,000 atoms. The mass will be the same too if the energy gained or lost is accounted for. Chemistry studies the interactions of these atoms, sometimes alone but more often combined with (bonded to) other atoms to form ions and compounds/molecules. These atoms interact with other atoms (e.g., a wood fire is the combination of oxygen atoms from the air with the carbon and hydrogen atoms in the wood) and they may also interact with light (a photograph is formed from the changes that light causes to the chemicals on a film) and other types of radiation. One surprisingly early finding was that these atoms almost always combine in definite ratios or proportions: silica sand is a structure where the ratio of silicon atoms to oxygen atoms is 1:2. We now know that there are exceptions to this law of definite proportions (integrated circuits are a good example). Another key discovery in chemistry was that when a specific chemical reaction occurs, the amount of energy gained or lost will always be the same. This leads to the important concepts of equilibrium, thermodynamics, and kinetics. Physical chemistry is grounded upon modern physics, and it is in principle possible to describe all chemical systems using the theory of quantum mechanics. This theory is mathematically complex and profoundly non-intuitive. In practice, however, only the simplest chemical systems may realistically be investigated in purely quantum mechanical terms, and approximations must be made for most practical purposes (e.g. Density functional theory). Hence a detailed understanding of quantum mechanics is not necessary for most chemistry, as the important implications of the theory (principally the orbital approximation) can be understood and applied in simpler terms. Although quantum mechanics may frequently be ignored, the fundamental concept behind it - quantisation of energy - may not. Chemists depend on quantum effects for - amongst other things - all spectroscopic techniques, although many may not realise it! Again, frequently the physics may be ignored, and the end result (e.g. an NMR Spectrum) interpreted nonetheless. A full physical description of chemistry must also take into account relativity, the other principle theory of modern physics, also mathematically complex. Fortunately, relativistic effects are only important in extremely precise calculations of atomic structure, mainly involving the heavier elements, and relativity is in practice irrelevant to almost all chemistry. Chemistry typically is divided into following major parts: analytical chemistry, the determination of substance composition and its constituents; organic chemistry, the study of carbon compounds; inorganic chemistry, dealing with broader elements not emphasized in organic chemistry; biochemistry, the study of chemistry in biological system; and physical chemistry, which forms the foundation of all other branches, encompassing the physical property of substances and the theoretical tools to investigate them. Other cross-disciplinary studies and specialization branches include: materials science, polymer chemistry, environmental chemistry, Pharmacy
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Houk Kaplan SAT II: Chemistry 2004-2005 by Kaplan Uncle Tungsten : Memories of a Chemical Boyhood by Oliver Sacks Recent Chemistry related patents From USPTO: 6718189: Method and apparatus for non-invasive blood analyte measurement with fluid compartment equilibration 6718152: Fully fluorinated polymer coated development electrodes 6718103: Apparatus and method for transmitting images over a single-filament fiber optic cable 6718083: Optical switch and router 6718008: X-ray diffraction screening system with retractable x-ray shield 6717973: Wavelength and bandwidth monitor for excimer or molecular fluorine laser 6717668: Simultaneous imaging and spectroscopy apparatus 6717657: Apparatus for measuring the volume of individual red blood cells 6717413: Contact potential difference ionization detector 6717364: Thallium free--metal halide lamp with magnesium halide filling for improved dimming properties 6717354: Electroluminescent materials 6717269: Integrated circuit device having sidewall spacers along conductors 6717193: Metal-insulator-metal (MIM) capacitor structure and methods of fabricating same 6717137: Systems and methods for inducing infrared multiphoton dissociation with a hollow fiber waveguide 6717136: Microfludic system (EDI) 6717130: Methods and apparatus for mass spectrometry 6717124: Autofocus z stage 6717119: Device for performing multiple chemical reactions and processes in high frequency fields 6717033: Poly ADP-ribose polymerase gene and its uses 6717032: Transgenic mice containing DEZ orphan receptor gene disruptions 6717031: Method for selecting a transgenic mouse model of alzheimer's disease 6717030: Protein kinase C epsilon as modulator of anxiety, alcohol consumption and self-administration of drugs of abuse 6717017: Total synthesis of antitumor acylfulvenes 6717016: Phosphine compound, transition metal complex containing the same phosphine compound as ligand and asymmetric synthesis catalyst containing the complex 6717015: Venlafaxine besylate 6717014: Processes for preparing haloamines and tertiary aminoalkylorganometallic compounds 6717011: Chiral diazaphospholidine ligands 6717008: Derivatives of C2-substituted indan-1-ol compounds, methods for their preparation and use 6717004: Method for making alkylhalosilanes 6717002: Method of producing steroid derivatives 6716999: Pyrone derivatives and method for producing same 6716998: Process for synthesis of 2-yl chroman derivatives 6716995: Design and synthesis of advanced NLO materials for electro-optic applications 6716994: Mobility-Modifying Cyanine Dyes 6716993: Polymethine compound and near-infrared absorbing material comprising same 6716992: Cycloaliphatic epoxy compounds containing styrenic, cinnamyl, or maleimide functionality 6716987: Derivatives of benzofuran or benzodioxazole compounds 6716986: Sulfuric acid mono-[3-({1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-YL}-hydroxy-methyl)-2- methoxy-phenyl]ester 6716985: Process for making paroxetine 6716984: Polymer-supported synthesis of heteroatom bidentate ligands for catalysis 6716983: S type 2-substituted hydroxy-2-indolidinylbutyric ester compounds and process for preparation thereof 6716982: Method for preparing camptothecin derivatives 6716980: Process to produce oxazolidinones 6716976: Process for selective oxidation of cellulose 6716975: Antisense modulation of EDG1 expression 6716974: Therapeutic and diagnostic methods and compositions based on jagged/notch proteins and nucleic acids 6716971: Pteridine nucleotide analogs 6716970: Water soluble, randomly substituted partial N-partial O-acetylated chitosan, preserving compositions containing chitosan, and processes for making thereof 6716969: Reactive dye compounds |