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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]
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 ...
WURCS GlycoCT PubChem CID G "Glycan Repository". 122194 Gmelin Gmelin database: Elsevier: inorganic and organometallic compounds closed access 1,500,000 G-SRS 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
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.
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 ...
Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and begins to melt above approximately 37 °C (99 °F), [ 2 ] and its boiling point is above 370 °C (698 °F). [ 2 ]
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.
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 ...