Definitions and Classification of Chemical Substances
- 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.
- Chemical substances can exist in different physical states or phases without changing their chemical composition.
- Substances transition between 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.
- Chemical substances can be organic or inorganic substances of a particular molecular identity.
- Chemical substances can occur as a result of a chemical reaction or in nature.
- Inorganic solid substances of uniform composition are known as minerals.
- Chemical substances in law can include pure substances and mixtures with a defined composition or manufacturing process.
- Polymers are often mixtures of molecules with different molar masses.
- The concept of a chemical substance was established in the late eighteenth century.
- An element is a chemical substance made up of a particular kind of atom.
- Elements cannot be broken down or transformed into a different element by a chemical reaction.
- There are 118 known elements, with about 80 of them being stable.
- Chemical compounds are composed of a specific set of atoms or ions.
- Mixtures contain more than one chemical substance and do not have a fixed composition.
- Chemical elements can be mixed together to form a mixture.
- Chemical substances and mixtures are often referred to as chemicals.
Naming and Indexing of Chemical Substances
- Chemical substances have systematic names according to IUPAC rules.
- The Chemical Abstracts Service (CAS) uses an alternative naming system.
- Many compounds have common, simpler names.
- Chemical substances can be indexed and identified using systematic or common names.
- Naming conventions help in the organization and identification of chemical substances.
- Chemical compounds are often given systematic names.
- Natural products and pharmaceuticals also have simpler names.
- Chemical compounds can be referred to using chemical formulae or molecular structures.
- Common methods of identifying chemical substances include using their common names, systematic names, chemical formulas, chemical structures, CAS registry numbers, and InChI.
- CAS registry numbers are numerical identifiers assigned to each chemical substance in the literature.
- The Chemical substances index is a database compiled by CAS that includes information on reported chemical substances.
- SMILES and InChI are computer-friendly systems developed for substance information.
- Identification of chemical substances is important for accurate referencing and tracking in the literature.
Isolation, Purification, Characterization, and Identification of Chemical Substances
- Pure substances often need to be isolated from mixtures, whether from natural sources or after chemical reactions.
- Isolation methods are used to separate desired substances from mixtures.
- Purification techniques are employed to remove impurities and obtain a higher level of substance purity.
- Characterization involves determining the properties and composition of a substance.
- Identification techniques are used to confirm the identity of a substance, such as spectroscopy or chromatography.
Measurement and Stoichiometry
- Stoichiometry is the study of the quantitative relationships between reactants and products in chemical reactions.
- The law of conservation of mass states that the total mass of reactants equals the total mass of products.
- Stoichiometry allows for the calculation of product amounts based on known reactant quantities.
- Stoichiometry can be used to determine quantities by weight in a reaction described by a balanced equation.
- Gas stoichiometry deals with reactions involving gases and uses volume ratios or molar masses for mass calculations.
Related Concepts
- Chemistry portal is a comprehensive resource for chemistry-related information.
- Hazard symbols are used to indicate the potential dangers associated with chemical substances.
- Homogeneous and heterogeneous mixtures are different types of mixtures.
- Prices of chemical elements can vary based on supply and demand.
- Dedicated bio-based chemicals are substances derived from renewable resources.
Chemical substance Data Sources
| Reference | URL |
|---|---|
| Glossary | https://www.alternix.com/blogs/glossary-of-terms/chemical-substance |
| Wikipedia | http://en.wikipedia.org/wiki/Chemical_substance |
| Wikidata | https://www.wikidata.org/wiki/Q79529 |
| Knowledge Graph | https://www.google.com/search?kgmid=/m/01q5f |
