## Chemistry

E-Mail Comments to: opencyc-doc@cyc.com
Last Update: 12/13/02
Copyright© 1996-2002. All rights reserved. See Terms of Usage.

Return to Documentation Contents
Return to Vocabulary Contents

At the present time, Cyc's representation of scientific chemistry is limited to certain basic relations between atoms, molecules, and substances. Most representations of complex substances in Cyc do not include chemical structures and formulae, or the axioms to reason about them. Rather, substances and their properties are represented at a more "everyday" level: creation, destruction, changes, and interactions are described and reasoned about, but the underlying mechanisms are not usually considered.

We have resisted the temptation to assert many detailed, ready-made axioms based on chemical reference material listing atomic weights, electronegativity values, chemical formulae, etc., because devising the supporting theoretical axioms to use those facts is neither easy nor of obvious value. Such is the case with many fundamental theories in science: connecting them to the real world is so hard that most scientific problems are solved by invoking more specific rules which apply to different kinds of situations.

The following constants and the representational techniques they embody may serve as a starting point for more complete representations of chemical substances as well as a more comprehensive chemical theory. For example, the functional specification of types of atoms and nuclei can be extended to cover isotopes.

### Elements And Atoms

#$ElementStuff chemical elements

> An instance of #$TangibleStuffCompositionType and a specialization of #$InanimateThing. Each instance of #$ElementStuff is a piece of tangible stuff, composed of a quantity of atoms, all of which are of the same chemical element. That is, every atom in a given piece of #$ElementStuff has the same number of protons in its atomic nucleus. For example, all pieces of carbon (i.e. all instances of #$Carbon) are instances of #$ElementStuff. On the other hand, instances of #$Water, because they are all constituted of both #$Hydrogen and #$Oxygen atoms, do not belong to the collection #$ElementStuff.
> guid: bd5908b9-9c29-11b1-9dad-c379636f7270
> direct instance of: #$TangibleStuffCompositionType
> direct specialization of: #$InanimateThing
> direct generalization of: #$UnalloyedMetal

#$ElementStuffTypeByNumberOfProtons types of chemical element classified by number of protons

> A collection of collections and a specialization of #$ElementStuffType. Each instance of #$ElementStuffTypeByNumberOfProtons is a specialization of #$ElementStuff which is defined _only_ by the atomic composition of its instances -- neither the isotopic composition or physical state of the substances, nor any other additional feature, determines membership in an instance of #$ElementStuffTypeByNumberOfProtons. All that matters is that the instances of that collection are entirely composed of atoms having a particular number of protons in each atomic nucleus. Thus, the collection #$Carbon is an instance of #$ElementStuffTypeByNumberOfProtons, but neither the collection #$Diamond nor the collection #$Graphite is (even though they are subcollections of #$Carbon), because their members have additional qualifications.
> guid: bd590830-9c29-11b1-9dad-c379636f7270
> direct instance of: #$SecondOrderCollection #$DisjointCollectionType #$AtemporalNecessarilyEssentialCollectionType
> direct specialization of: #$ElementStuffType #$ChemicalSubstanceType
> direct generalization of: #$NobleGasElement

#$atomicNumber atomic number (predicate that is functional in its second argument) (functional predicate) (binary predicate)

> This predicate relates an atomic number to an element. (#$atomicNumber ELEMENT INT) means that ELEMENT, an instance of #$ElementStuffTypeByNumberOfProtons, has the #$PositiveInteger INT for its atomic number. This means that any instance of (#$AtomFn ELEMENT) must have INT many protons (see #$Proton) in its atomic nucleus (see #$AtomicNucleus). For example, (#$atomicNumber #$Carbon 6) means that every instance of (#$AtomFn #$Carbon) has six protons in its nucleus.
> guid: bd5890dc-9c29-11b1-9dad-c379636f7270
> direct instance of: #$StrictlyFunctionalSlot

#$AtomFn atom fn

> An instance of both #$CollectionDenotingFunction and #$ReifiableFunction. When applied to an instance ELEMENT-TYPE of #$ElementStuffType, #$AtomFn returns the collection of all atoms (see #$Atom) of ELEMENT-TYPE. Each instance of the collection (#$AtomFn ELEMENT-TYPE) is an atom with N protons in its atomic nucleus, where N is the #$atomicNumber (q.v.) of ELEMENT-TYPE. For example, (#$AtomFn #$Carbon) is the collection of all carbon atoms, each of which has 6 protons in its nucleus. Additionally, each atom has a #$massNumberOfAtom (which need not be same for all atoms of the same #$ElementStuffType : see #$IsotopeFn).
> guid: c0fcf284-9c29-11b1-9dad-c379636f7270
> direct instance of: #$UnaryFunction #$CollectionDenotingFunction #$ReifiableFunction #$Individual

#$Atom atoms (inanimate objects) (tangible things) (things with a location)

> A specialization of #$ChemicalObject. Each instance of #$Atom is a microscopic-scale object with exactly one atomic nucleus (see #$AtomicNucleus) and some number of electrons (see #$Electron). A typical instance of #$Atom has no net charge, i.e., it has as many instances of #$Electron as it does of #$Proton. For the collection of atoms that do have non-zero charges, see #$AtomicIon.
> guid: bd5891ef-9c29-11b1-9dad-c379636f7270
> direct instance of: #$ExistingObjectType
> direct specialization of: #$ChemicalObject

#$NucleusFn nucleus fn **COMMENT NOT REVIEWED** **GAFs NOT REVIEWED**

> #$NucleusFn is a Cyc function, specifically a #$CollectionDenotingFunction. #$NucleusFn takes an instance of #$ElementStuffTypeByNumberOfProtons (q.v.) as its single argument and returns a collection of all the atomic nucleii belonging to element-stuff of that type. Thus, (#$NucleusFn E) denotes a subcollection of #$AtomicNucleus whose elements all have the same number of protons. For example, (#$NucleusFn #$Carbon) is the collection of #$Carbon nuclei, each of which has six protons.
> guid: c0fcee23-9c29-11b1-9dad-c379636f7270
> direct instance of: #$UnaryFunction #$CollectionDenotingFunction #$ReifiableFunction #$Individual

#$AtomicNucleus atomic nuclei

> A specialization of #$MicroscopicScaleObject. Each instance of #$AtomicNucleus is an object composed of some definite number of instances of #$Proton and some definite number of instances of #$Neutron. Each instance of #$Atom has exactly one instance of #$AtomicNucleus as a part.
> guid: bd58a3d9-9c29-11b1-9dad-c379636f7270
> direct instance of: #$ExistingObjectType
> direct specialization of: #$MicroscopicScaleObject

### Sub

#$SubAtomicParticle subatomic particles

> A specialization #$MicroscopicScaleObject and #$InanimateObject-Natural. Each instance of #$SubAtomicParticle is a physical particle smaller than the smallest atom. Major subcollections of #$SubAtomicParticle include #$Electron, #$Proton, and #$Neutron.
> guid: bd58db74-9c29-11b1-9dad-c379636f7270
> direct instance of: #$ExistingObjectType
> direct specialization of: #$MicroscopicScaleObject #$InanimateObject-Natural
> direct generalization of: #$Nucleon

#$Electron electrons

> A specialization of #$Lepton. Each instance of #$Electron is a subatomic particle with an #$ElectricalCharge of -1. Each instance of #$Atom consists of a nucleus (see #$AtomicNucleus) surrounded by a cloud of negatively charged electrons.
> guid: bd5881d3-9c29-11b1-9dad-c379636f7270
> direct instance of: #$ExistingObjectType
> direct specialization of: #$Individual

#$Nucleon nucleons

> A specialization of #$SubAtomicParticle. Each instance of #$Nucleon is a subatomic particle found in some atomic nucleus (see the collection #$AtomicNucleus). #$Nucleon has two subcollections, #$Proton and #$Neutron. Every instance of #$AtomicNucleus is composed of some number of #$Nucleons.
> guid: bd588191-9c29-11b1-9dad-c379636f7270
> direct instance of: #$ExistingObjectType
> direct specialization of: #$SubAtomicParticle
> direct generalization of: #$Neutron #$Proton

#$Proton protons **COMMENT NOT REVIEWED** **GAFs NOT REVIEWED**

> A specialization of #$Nucleon. Each instance of #$Proton is a nucleon which has an #$ElectricalCharge of +1.
> guid: bd58814d-9c29-11b1-9dad-c379636f7270
> direct instance of: #$ExistingObjectType
> direct specialization of: #$Nucleon

#$Neutron neutrons

> A specialization of #$Nucleon. Each instance of #$Neutron is a nucleon with an electrical charge of 0.
> guid: bd588216-9c29-11b1-9dad-c379636f7270
> direct instance of: #$ExistingObjectType
> direct specialization of: #$Nucleon

### Chemical Compounds Molecules

#$ChemicalObject chemical objects

> A specialization of #$MicroscopicScaleObject. Each instance of #$ChemicalObject is an object whose behavior is typically described in terms of its outer cloud of #$Electrons. Specializations of #$ChemicalObject include the collections #$Atom, #$Molecule, and #$Ion.
> guid: bd58916a-9c29-11b1-9dad-c379636f7270
> direct instance of: #$ExistingObjectType
> direct specialization of: #$MicroscopicScaleObject
> direct generalization of: #$Molecule #$Atom

#$Molecule molecules

> A subcollection of #$ChemicalObject and #$ComplexPhysicalObject. Each instance of #$Molecule is a microscopic-scale object whose component atoms are all chemically bonded to each other; typically, this means that the atoms are covalently bonded. Examples: some instances of #$Molecule, including molecules of oxygen (O2), ozone (O3), water (H2O), carbon monoxide (CO), carbon dioxide (CO2), etc., contain covalently bonded atoms belonging to the collection #$Oxygen. Some highly complex examples of #$Molecule are those belonging to the collection #$DNAMolecule. See also #$MoleculeFn. Note: #$Diamond and other macroscopic covalent solids are excluded from belonging to #$Molecule by the constraint that instances of #$Molecule are microscopic.
> guid: bd58f0b2-9c29-11b1-9dad-c379636f7270
> direct instance of: #$ExistingObjectType
> direct specialization of: #$ComplexPhysicalObject #$ChemicalObject

#$Ion ions **COMMENT NOT REVIEWED** **GAFs NOT REVIEWED**

> A collection of microscopic-scale objects; a subset of #$ChemicalObject. Every instance of #$Ion is an atom or radical which has either a negative or positive net electrical charge, due to having either more or fewer electrons than there are protons in its nuclei. Note: atomic ions violate Cyc's default assumption that instances of #$Atom have a net electrical charge of zero, so #$Ion constitutes a class of exceptions to that rule.
> guid: c0fbae39-9c29-11b1-9dad-c379636f7270
> direct instance of: #$ExistingObjectType
> direct specialization of: #$ChemicalObject

#$ChemicalSubstanceType chemical substances **COMMENT NOT REVIEWED**

> A collection of collections and a specialization of #$TangibleStuffCompositionType. Each instance of #$ChemicalSubstanceType is a specialization of #$PartiallyTangible whose instances are defined _only_ by their chemical composition -- not by their physical state or any other property. Instances of #$ChemicalSubstanceType can be of two varieties: (1) Collections whose instances are completely uniform with each other in terms of chemical composition; this includes (a) the chemical elements -- such as #$Carbon, #$Oxygen, and #$Hydrogen -- which are instances of #$ElementStuffTypeByNumberOfProtons (thus, the latter is a specialization of #$ChemicalSubstanceType), and (b) chemical compounds constituted of more than one substance chemically bonded, e.g., #$Water, #$Caffeine, and #$IronOxide, which are instances of #$ChemicalCompoundTypeByChemicalSpecies (2) Substances which have a general chemical specification, that is, whose instances do not have exactly the same chemical composition but fall within certain specifications, e.g., #$DNAStuff. Note that collections that are _not_ instances of #$ChemicalSubstanceType include collections of substances which have some component which is of overriding significance in some context, so that in everyday language such substances are frequently referred to by the name of their important component (e.g., penicillin applied to a tablet containing penicillin), but which have significant admixtures of other substances. Thus, #$Penicillin is an instance of #$ChemicalSubstanceType, but the collection of tablets containing penicillin and including other ingredients is not. Also, specializations of #$Mixture, such as #$Lemonade, are _not_ instances of #$ChemicalSubstanceType, because mixtures are determined by their physical state rather than solely by their chemical composition.
> guid: bd58cd95-9c29-11b1-9dad-c379636f7270
> direct instance of: #$SiblingDisjointCollectionType #$SecondOrderCollection #$AtemporalNecessarilyEssentialCollectionType
> direct specialization of: #$TangibleStuffCompositionType
> direct generalization of: #$ElementStuffTypeByNumberOfProtons

#$MolecularStuff molecular stuff **COMMENT NOT REVIEWED** **GAFs NOT REVIEWED**

> A collection of tangible stuff. Every instance of #$MolecularStuff is a portion of stuff composed of covalently-bonded molecules. Thus, #$Water and #$DNAStuff are subcollections of #$MolecularStuff; each of their instances consists of covalently bonded molecules. But instances of #$Salt-NaCl are not examples of #$MolecularStuff. Also, #$Oxygen is not a subcollection of #$MolecularStuff, since #$Oxygen denotes anything composed of that element, not just O2 (molecular oxygen) and O3 (ozone).
> guid: bd59e38c-9c29-11b1-9dad-c379636f7270
> direct instance of: #$TangibleStuffCompositionType
> direct specialization of: #$PartiallyTangible

#$MoleculeFn molecule fn

> A function that takes as an argument an instance CHEM-TYPE of #$ChemicalSubstanceType and returns the collection of all molecules of CHEM-TYPE. For example, (#$MoleculeFn #$Water) is the collection of all water molecules.
> guid: c0fcede2-9c29-11b1-9dad-c379636f7270
> direct instance of: #$MacroRelation #$UnaryFunction #$CollectionDenotingFunction #$ReifiableFunction #$Individual

#$MicroscopicScaleObject microscopic objects

> A specialization of #$PartiallyTangible. Each instance of #$MicroscopicScaleObject is a partially tangible object which is so small that human beings cannot perceive it, except (perhaps) with the use of special devices such as #$Microscopes or #$ElectronMicroscopes. Specializations of #$MicroscopicScaleObject include #$Molecule, #$Atom, #$SubAtomicParticle, #$Chloroplast, and #$Mitochondrion.
> guid: bd5891ac-9c29-11b1-9dad-c379636f7270
> direct instance of: #$TemporalStuffType
> direct specialization of: #$PartiallyTangible
> direct generalization of: #$SubAtomicParticle #$ChemicalObject #$AtomicNucleus #$CellPart #$Microorganism

### Metal

#$Metal metals

> An instance of #$TangibleStuffCompositionType. Every instance of #$Metal is a tangible object having certain characteristic physical and chemical properties. Instances of #$Metal are good conductors of electricity and heat, and most instances of #$Metal are solids at room temperature (although all instances of #$Mercury, for example, are liquids at room temperature). Solid instances of #$Metal have a shiny luster, and are highly malleable. Specializations of #$Metal include #$Mercury, #$Potassium, #$Brass, #$Lead, and #$Iron.
> guid: bd58ac39-9c29-11b1-9dad-c379636f7270
> direct instance of: #$ProductByGenericType #$TangibleStuffCompositionType
> direct specialization of: #$ElectricalConductor #$InorganicStuff
> direct generalization of: #$UnalloyedMetal #$MetalAlloy

#$MetalAlloy alloys

> A collection of tangible stuffs; a subcollection of #$Metal. Each instance of #$MetalAlloy is a metallic stuff which is a homogeneous blend of at least one part of #$UnalloyedMetal with at least one other substance. #$MetalAlloy is not a subcollection of #$Mixture, because each instance of #$MetalAlloy is defined not only by the amounts and kinds of its #$constituents, but also (unlike a mixture) by the internal structures formed during its creation. Furthermore, the creation process is typically more complex than #$Mixing. Common metal alloys include the instances of #$Bronze-Stuff, #$Brass, and #$Steel. Note that #$GalvanizedMetal is _not_ a subcollection of #$MetalAlloy, because every instance of #$GalvanizedMetal has a coating of some #$Zinc on its surface, and thus (unlike an alloy) the components of galvanized metals are not homogenously distributed throughout.
> guid: bd58cc8b-9c29-11b1-9dad-c379636f7270
> direct instance of: #$TangibleStuffCompositionType
> direct specialization of: #$SolidTangibleThing #$Mixture #$ArtificialMaterial #$Metal

#$UnalloyedMetal unalloyed metals **COMMENT NOT REVIEWED** **GAFs NOT REVIEWED**

> A collection of tangible stuffs; a subcollection of #$Metal. Every instance of #$UnalloyedMetal is a metal which is also an element, i.e., a substance of unmixed chemical type. Thus, each subcollection of #$UnalloyedMetal is a subcollection of both #$Metal and #$ElementStuff. Examples of #$UnalloyedMetal include #$Gold, #$Iron, #$Uranium, #$Antimony, #$Titanium, and many more.
> guid: bd5908f8-9c29-11b1-9dad-c379636f7270
> direct instance of: #$TangibleStuffCompositionType
> direct specialization of: #$Metal #$ElementStuff

#$NobleGasElement noble gases

> A specialization of ElementStuffTypeByNumberOfProtons. Each instance of #$NobleGasElement is a type of element that does _not_ readily form compounds with other types of elements. Instances of #$NobleGasElement are highly stable, due to the fact that they have the maximum number of electrons possible in their outer shell. The six instances of #$NobleGasElement are #$Helium, #$Neon, #$Argon, #$Krypton, #$Xenon, and #$Radon.
> guid: bd58c01f-9c29-11b1-9dad-c379636f7270
> direct instance of: #$SecondOrderCollection
> direct specialization of: #$ElementStuffTypeByNumberOfProtons

### Chemical Reactions

#$ChemicalReaction chemical reactions **COMMENT NOT REVIEWED** **GAFs NOT REVIEWED**

> A collection of events; a subcollection of #$PhysicalTransformationEvent. Each instance of #$ChemicalReaction is an event in which two or more substances undergo a chemical change, i.e., some portions of the substances involved are transformed into different #$ChemicalCompoundTypes. The transformations are brought about by purely chemical (including biochemical) means which affect chemical bonds between atoms in the molecules of stuff, rather than by physical means, biological means, or purposeful planning, etc. Examples of #$ChemicalReaction : instances of #$CombustionProcess; instances of #$Photosynthesis-Generic.
> guid: bd589bc8-9c29-11b1-9dad-c379636f7270
> direct instance of: #$DefaultDisjointScriptType #$TemporalObjectType
> direct specialization of: #$ChemicalInteraction #$PhysicalTransformationEvent
> direct generalization of: #$BiologicalMetabolismEvent

#$catalyst catalyst (actor slot) (role) (extensional representation predicate) **COMMENT NOT REVIEWED** **GAFs NOT REVIEWED**

> The predicate #$catalyst identifies the particular thing that acts as a catalyst in a particular chemical reaction. (#$catalyst R X) means that the #$ChemicalReaction R has the particular quantity of substance X as a catalyst. For example, every instance of #$Photosynthesis-Generic has some portion of #$Chlorophyll as a catalyst; an amount of #$Water may be a #$catalyst in some #$OxidationProcess of a #$Metal.
> guid: be011804-9c29-11b1-9dad-c379636f7270
> direct instance of: #$IndividualLevelPredicate #$ActorSlot
> direct specialization of: #$unchangedActors

### Purity

#$PureFn pure fn **COMMENT NOT REVIEWED** **GAFs NOT REVIEWED**

> An instance of #$CollectionDenotingFunction. (#$PureFn X) denotes the subcollection of the #$ChemicalSubstanceType X whose instances are chemically pure. Note that #$PureFn can be applied only to instances of #$ChemicalSubstanceType (such as #$Fructose or #$Water), but not to mixtures (such as #$Air). See also #$PureSubstance.
> guid: c0fbb1ad-9c29-11b1-9dad-c379636f7270
> direct instance of: #$UnaryIntersectionFunction #$Individual

#$PureSubstance pure substances **COMMENT NOT REVIEWED** **GAFs NOT REVIEWED**

> A collection of tangible stuffs. Each instance of #$PureSubstance is a chemically pure portion of stuff belonging to some particular #$ChemicalSubstanceType (e.g. #$Water or #$Cellulose). `Chemically pure' applies to a piece of stuff which has no sub-portions that fail to conform to the chemical composition of its (single) #$ChemicalSubstanceType. In typical contexts, most common portions of a #$ChemicalSubstanceType will not be instances of #$PureSubstance . For example, a piece of pencil lead, though mostly carbon, will not be an instance since it is not pure carbon and any portion of ordinary tap water will contain too many impurities. Many sub-portions of either a piece of pencil lead or portion of tap water will fail to conform to the chemical composition of either carbon or water. Some instances of #$ChemicalSubstanceType are subcollections of #$PureSubstance in most contexts but not in all. In typical domestic contexts, for example, a piece of ordinary distilled water would be an instance of #$PureSubstance . However, in a clean room or microchip manufacturing context, ordinary distilled water would probably be considerd impure (see #$ImpureCompound). In general, to refer to a pure instance of a substance one can use the function #$PureFn, e.g. (#$PureFn #$Carbon). Note that #$PureFn has #$PureSubstance as a #$resultGenl . Since this kind of purity is relative to specified chemical composition only, #$PureSubstance (and #$PureFn) does not pertain to mixtures in Cyc (such as #$Air). Cf. #$Mixture, #$ChemicalSubstanceType. See also #$PureSubstanceType and #$ImpureCompound.
> guid: c0fbb161-9c29-11b1-9dad-c379636f7270
> direct instance of: #$TangibleStuffCompositionType
> direct specialization of: #$InanimateThing

#$PureSubstanceType types of pure substance

> An instance of #$SecondOrderCollection. Each instance of #$PureSubstanceType is both a specialization of #$PureSubstance (q.v.) and a specialization of some instance of #$ChemicalSubstanceType (q.v.). Each instance of #$PureSubstanceType is characterized by the properties of the instance of #$ChemicalSubstanceType of which it is a specialization, and by the fact that each of its instances is chemically pure.
> guid: c0fbb120-9c29-11b1-9dad-c379636f7270
> direct instance of: #$SecondOrderCollection
> direct specialization of: #$TangibleStuffCompositionType

Copyright© 1996-2002. All rights reserved. See Terms of Usage.