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Chemistry
Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during chemical reaction, reactions with other chemical substance, substances. Chemistry also addresses the nature of chemical bonds in chemical compounds. In the scope of its subject, chemistry occupies an intermediate position between physics and biology. It is sometimes called the central science because it provides a foundation for understanding both Basic research, basic and Applied science, applied scientific disciplines at a fundamental level. 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 prop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Chemical Society
The American Chemical Society (ACS) is a scientific society based in the United States that supports scientific inquiry in the field of chemistry. Founded in 1876 at New York University, the ACS currently has more than 155,000 members at all degree levels and in all fields of chemistry, chemical engineering, and related fields. It is one of the world's largest scientific societies by membership. The ACS is a 501(c) organization, 501(c)(3) non-profit organization and holds a congressional charter under Title 36 of the United States Code. Its headquarters are located in Washington, D.C., and it has a large concentration of staff in Columbus, Ohio. The ACS is a leading source of scientific information through its peer-reviewed scientific journals, national conferences, and the Chemical Abstracts Service. Its publications division produces over 80 Scientific journal, scholarly journals including the prestigious ''Journal of the American Chemical Society'', as well as the weekly tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Reaction
A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, energy change as new products are generated. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the Atomic nucleus, nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive Chemical element, elements where both electronic and nuclear changes can occur. The substance (or substances) initially involved in a chemical reaction are called reagent, reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more Product (c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alchemy
Alchemy (from the Arabic word , ) is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practised in China, India, the Muslim world, and Europe. In its Western form, alchemy is first attested in a number of pseudepigraphical texts written in Greco-Roman Egypt during the first few centuries AD.. Greek-speaking alchemists often referred to their craft as "the Art" (τέχνη) or "Knowledge" (ἐπιστήμη), and it was often characterised as mystic (μυστική), sacred (ἱɛρά), or divine (θɛíα). Alchemists attempted to purify, mature, and perfect certain materials. Common aims were chrysopoeia, the transmutation of " base metals" (e.g., lead) into "noble metals" (particularly gold); the creation of an elixir of immortality; and the creation of panaceas able to cure any disease. The perfection of the human body and soul was thought to result from the alchemical ''magnum opus'' ("Great Work"). The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Central Science
Chemistry is often called the central science because of its role in connecting the physical sciences, which include chemistry, with the life sciences, pharmaceutical sciences and applied sciences such as medicine and engineering. The nature of this relationship is one of the main topics in the philosophy of chemistry and in scientometrics. The phrase was popularized by its use in a textbook by Theodore L. Brown and H. Eugene LeMay, titled ''Chemistry: The Central Science'', which was first published in 1977, with a fifteenth edition published in 2021. The central role of chemistry can be seen in the systematic and hierarchical classification of the sciences by Auguste Comte. Each discipline provides a more general framework for the area it precedes (mathematics → astronomy → physics → chemistry → biology → social sciences). Balaban and Klein have more recently proposed a diagram showing the partial ordering of sciences in which chemistry may be argued is "the central ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Bond
A chemical bond is the association of atoms or ions to form molecules, crystals, and other structures. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds, or some combination of these effects. Chemical bonds are described as having different strengths: there are "strong bonds" or "primary bonds" such as covalent, ionic and metallic bonds, and "weak bonds" or "secondary bonds" such as dipole–dipole interactions, the London dispersion force, and hydrogen bonding. Since opposite electric charges attract, the negatively charged electrons surrounding the nucleus and the positively charged protons within a nucleus attract each other. Electrons shared between two nuclei will be attracted to both of them. "Constructive quantum mechanical wavefunction interference" stabilizes the paired nuclei (see Theories of chemical bonding). Bonded nuclei maintain an optima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element is therefore not a compound. A compound can be transformed into a different substance by a chemical reaction, which may involve interactions with other substances. In this process, bonds between atoms may be broken or new bonds formed or both. There are four major types of compounds, distinguished by how the constituent atoms are bonded together. Molecular compounds are held together by covalent bonds; ionic compounds are held together by ionic bonds; intermetallic compounds are held together by metallic bonds; coordination complexes are held together by coordinate covalent bonds. Non-stoichiometric compounds form a disputed marginal case. A chemical formula specifies the number of atoms of each element in a compound molecule, usin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atom
Atoms are the basic particles of the chemical elements. An atom consists of a atomic nucleus, nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other by the number of protons that are in their atoms. For example, any atom that contains 11 protons is sodium, and any atom that contains 29 protons is copper. Atoms with the same number of protons but a different number of neutrons are called isotopes of the same element. Atoms are extremely small, typically around 100 picometers across. A human hair is about a million carbon atoms wide. Atoms are smaller than the shortest wavelength of visible light, which means humans cannot see atoms with conventional microscopes. They are so small that accurately predicting their behavior using classical physics is not possible due to quantum mechanics, quantum effects. More than 99.94% of an atom's mass is in the nucleus. Protons hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecule
A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemistry, and biochemistry, the distinction from ions is dropped and ''molecule'' is often used when referring to polyatomic ions. A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O2); or it may be heteronuclear, a chemical compound composed of more than one element, e.g. water (molecule), water (two hydrogen atoms and one oxygen atom; H2O). In the kinetic theory of gases, the term ''molecule'' is often used for any gaseous particle regardless of its composition. This relaxes the requirement that a molecule contains two or more atoms, since the noble gases are individual atoms. Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Element
A chemical element is a chemical substance whose atoms all have the same number of protons. The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8: each oxygen atom has 8 protons in its atomic nucleus, nucleus. Atoms of the same element can have different numbers of neutrons in their nuclei, known as isotopes of the element. Two or more atoms can combine to form molecules. Some elements form Homonuclear molecule, molecules of atoms of said element only: e.g. atoms of hydrogen (H) form Diatomic molecule, diatomic molecules (H). Chemical compounds are substances made of atoms of different elements; they can have molecular or non-molecular structure. Mixtures are materials containing different chemical substances; that means (in case of molecular substances) that they contain different types of molecules. Atoms of one element can be transformed into atoms of a different element in nuclear reactions, which change an atom's at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Substance
A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be combined without reacting, they may form a chemical mixture. If a mixture is separated to isolate one chemical substance to a desired degree, the resulting substance is said to be chemically pure. Chemical substances can exist in several different physical states or phases (e.g. solids, liquids, gases, or plasma) without changing their chemical composition. Substances transition between these phases of matter in response to changes in temperature or pressure. Some chemical substances can be combined or converted into new substances by means of chemical reactions. Chemicals that do not possess this ability are said to be inert. Pure water is an example of a chemical substance, with a constant composition of two hydrogen atoms bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Science
Physical science is a branch of natural science that studies non-living systems, in contrast to life science. It in turn has many branches, each referred to as a "physical science", together is called the "physical sciences". Definition Physical science can be described as all of the following: * A branch of science (a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe)."... modern science is a discovery as well as an invention. It was a discovery that nature generally acts regularly enough to be described by laws and even by mathematics; and required invention to devise the techniques, abstractions, apparatus, and organization for exhibiting the regularities and securing their law-like descriptions." —p.vii, J. L. Heilbron, (2003, editor-in-chief). ''The Oxford Companion to the History of Modern Science''. New York: Oxford University Press. . * A branch of natural science – nat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemistry (word)
The word chemistry derives from the word alchemy, which is found in various forms in European languages. The word 'alchemy' itself derives from the Arabic word ''al-kīmiyāʾ'' (), wherein ''al-'' is the definite article 'the'. The ultimate origin of the word is uncertain, but the Arabic term ''kīmiyāʾ'' () is likely derived from either the Ancient Greek word ''khēmeia'' () or the similar ''khēmia'' ()."alchemy", entry in ''The Oxford English Dictionary'', J. A. Simpson and E. S. C. Weiner, vol. 1, 2nd ed., 1989, . The Greek term ''khēmeia'', meaning "cast together" may refer to the art of alloying metals, from root words χύμα (khúma, "fluid"), from χέω (khéō, "I pour"). Alternatively, ''khēmia'' may be derived from the ancient Egyptian name of Egypt, ''khem'' or ''khm'', ''khame'', or ''khmi'', meaning "blackness", likely in reference to the rich dark soil of the Nile river valley. Overview There are two main views on the derivation of the Greek word. Accord ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
