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PubChem can be accessed for free through a web user interface. Millions of compound structures and descriptive datasets can be freely downloaded via FTP. PubChem contains multiple substance descriptions and small molecules with fewer than 100 atoms and 1,000 bonds. More than 80 database vendors contribute to the growing PubChem database. [2]
Global Substance Registration System: CAS PubChem ChEMBL INN UNII "G-SRS". 109,260 GMD Golm Metabolome Database GC/MS of metabolites "GMD". Guide to PHARMACOLOGY IUPHAR: drugs and targets INN CAS ChEBI ChEMBL DrugBank PubChem "Guide to PHARMACOLOGY". Henry's law constants Max Planck Institute for Chemistry: volatile compounds Henry's law constants
mixtures have variable compositions, while compounds have a fixed, definite formula. when mixed, individual substances keep their properties in a mixture, while if they form a compound their properties can change. [10] The following table shows the main properties and examples for all possible phase combinations of the three "families" of ...
For example, a chemical database might store a molecule with stereochemistry unspecified, whereas a chemical registry system requires the registrar to specify whether the stereo configuration is unknown, a specific (known) mixture, or racemic. Each of these would be considered a different record in a chemical registry system.
The intermixture of ingredients in a composition of matter may be produced by mechanical or chemical operations, and its result may be a compound substance resolvable into its constituent elements by mechanical processes, or a new substance which can be destroyed only by chemical analysis. [4]
For these substances, it may be difficult to draw the line between a mixture and a compound, as in the case of palladium hydride. Broader definitions of chemicals or chemical substances can be found, for example: "the term 'chemical substance' means any organic or inorganic substance of a particular molecular identity, including – (i) any ...
Chemistry is the scientific study of the properties and behavior of matter. [1] It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during reactions with other substances.
Chemical formulas can be used to describe the relative amounts of elements present in a compound. For example, the chemical formula for water is H 2 O: this means that each molecule of water is constituted by 2 atoms of hydrogen (H) and 1 atom of oxygen (O). The chemical composition of water may be interpreted as a 2:1 ratio of hydrogen atoms ...