Carbon chauvinism is a neologism meant to disparage the assumption that the chemical processes of hypothetical extraterrestrial life must be constructed primarily from carbon (organic compounds) because as far as is known, carbon's chemical and thermodynamic properties render it far superior to all other elements at forming molecules used in living organisms. [1]
The expression "carbon chauvinism" is also used to criticize the idea that artificial intelligence cannot in theory be sentient or truly intelligent because the underlying matter is not biological. [2] Furthermore, the term is used by transhumanists to object to the commonly held view that life has an inherently higher moral value than hypothetical artificial consciousness. [3]
The term was used as early as 1973, when scientist Carl Sagan described it and other human chauvinisms that limit imagination of possible extraterrestrial life. [4] It suggests that human beings, as carbon-based life forms who have never encountered any life that has evolved outside the Earth's environment, may find it difficult to envision radically different biochemistries. [5]
Like carbon, silicon can form four stable bonds with itself and other elements, and long chemical chains known as silane polymers, which are very similar to the hydrocarbons essential to life on Earth. Silicon is more reactive than carbon, which could make it optimal for extremely cold environments. [6] However, silanes spontaneously burn in the presence of oxygen at relatively low temperatures, so an oxygen atmosphere may be deadly to silicon-based life. On the other hand, it is worth considering that alkanes are as a rule quite flammable, but carbon-based life on Earth does not store energy directly as alkanes, but as sugars, lipids, alcohols, and other hydrocarbon compounds with very different properties. Water as a solvent would also react with silanes, but again, this only matters if for some reason silanes are used or mass-produced by such organisms.
Silicon lacks an important property of carbon: single, double, and triple carbon-carbon bonds are all relatively stable. Aromatic carbon structures underpin DNA, which could not exist without this property of carbon. By comparison, compounds containing silene double bonds (such as silabenzene, an unstable analogue of benzene) exhibit far lower stability than the equivalent carbon compound. A pair of silane single bonds have significantly greater total enthalpy than a single silene double bond, so simple disilenes readily autopolymerise, and silicon favors the formation of linear chains of single bonds (see the double bond rule).
Hydrocarbons and organic compounds are abundant in meteorites, comets, and interstellar clouds, while their silicon analogs have never been observed in nature. Silicon does, however, form complex one-, two- and three-dimensional polymers in which oxygen atoms form bridges between silicon atoms. These are termed silicates. They are both stable and abundant under terrestrial conditions, and have been proposed as a basis for a pre-organic form of evolution on Earth (see clay hypothesis).
In organic chemistry, an alkane, or paraffin, is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carbon–carbon bonds are single. Alkanes have the general chemical formula CnH2n+2. The alkanes range in complexity from the simplest case of methane, where n = 1, to arbitrarily large and complex molecules, like pentacontane or 6-ethyl-2-methyl-5-(1-methylethyl) octane, an isomer of tetradecane.
In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or in the terminal position. Terminal alkenes are also known as α-olefins.
Several forms of biochemistry are agreed to be scientifically viable but are not proven to exist at this time. The kinds of living organisms currently known on Earth all use carbon compounds for basic structural and metabolic functions, water as a solvent, and DNA or RNA to define and control their form. If life exists on other planets or moons it may be chemically similar, though it is also possible that there are organisms with quite different chemistries – for instance, involving other classes of carbon compounds, compounds of another element, or another solvent in place of water.
In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest of the molecule's composition. This enables systematic prediction of chemical reactions and behavior of chemical compounds and the design of chemical synthesis. The reactivity of a functional group can be modified by other functional groups nearby. Functional group interconversion can be used in retrosynthetic analysis to plan organic synthesis.
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic; their odor is usually faint, and may be similar to that of gasoline or lighter fluid. They occur in a diverse range of molecular structures and phases: they can be gases, liquids, low melting solids or polymers.
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-containing compounds such as alkanes and its derivatives are universally considered organic, but many others are sometimes considered inorganic, such as halides of carbon without carbon-hydrogen and carbon-carbon bonds, and certain compounds of carbon with nitrogen and oxygen.
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms. Study of structure determines their structural formula. Study of properties includes physical and chemical properties, and evaluation of chemical reactivity to understand their behavior. The study of organic reactions includes the chemical synthesis of natural products, drugs, and polymers, and study of individual organic molecules in the laboratory and via theoretical study.
Silane (Silicane) is an inorganic compound with chemical formula SiH4. It is a colorless, pyrophoric, toxic gas with a sharp, repulsive, pungent smell, somewhat similar to that of acetic acid. Silane is of practical interest as a precursor to elemental silicon. Silane with alkyl groups are effective water repellents for mineral surfaces such as concrete and masonry. Silanes with both organic and inorganic attachments are used as coupling agents. They are commonly used to apply coatings to surfaces or as an adhesion promoter.
In chemical nomenclature, the IUPAC nomenclature of organic chemistry is a method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC). It is published in the Nomenclature of Organic Chemistry. Ideally, every possible organic compound should have a name from which an unambiguous structural formula can be created. There is also an IUPAC nomenclature of inorganic chemistry.
In chemistry, catenation is the bonding of atoms of the same element into a series, called a chain. A chain or a ring may be open if its ends are not bonded to each other, or closed if they are bonded in a ring. The words to catenate and catenation reflect the Latin root catena, "chain".
In organic chemistry, a substituent is one or a group of atoms that replaces atoms, thereby becoming a moiety in the resultant (new) molecule.
In inorganic chemistry, silenes, or disilalkenes, are silicon compounds that contain Si=Si double bonds, where the oxidation state of Si is +2. The parent molecule is disilene, Si2H4.
In chemistry, the carbon–hydrogen bond is a chemical bond between carbon and hydrogen atoms that can be found in many organic compounds. This bond is a covalent, single bond, meaning that carbon shares its outer valence electrons with up to four hydrogens. This completes both of their outer shells, making them stable.
Carbon is a primary component of all known life on Earth, and represents approximately 45–50% of all dry biomass. Carbon compounds occur naturally in great abundance on Earth. Complex biological molecules consist of carbon atoms bonded with other elements, especially oxygen and hydrogen and frequently also nitrogen, phosphorus, and sulfur.
A cyclic compound is a term for a compound in the field of chemistry in which one or more series of atoms in the compound is connected to form a ring. Rings may vary in size from three to many atoms, and include examples where all the atoms are carbon, none of the atoms are carbon, or where both carbon and non-carbon atoms are present. Depending on the ring size, the bond order of the individual links between ring atoms, and their arrangements within the rings, carbocyclic and heterocyclic compounds may be aromatic or non-aromatic; in the latter case, they may vary from being fully saturated to having varying numbers of multiple bonds between the ring atoms. Because of the tremendous diversity allowed, in combination, by the valences of common atoms and their ability to form rings, the number of possible cyclic structures, even of small size numbers in the many billions.
Organosilicon chemistry is the study of organometallic compounds containing carbon–silicon bonds, to which they are called organosilicon compounds. Most organosilicon compounds are similar to the ordinary organic compounds, being colourless, flammable, hydrophobic, and stable to air. Silicon carbide is an inorganic compound.
Silanes are saturated chemical compounds with the empirical formula SixHy. They are hydrosilanes, a class of compounds that includes compounds with Si−H and other Si−X bonds. All contain tetrahedral silicon and terminal hydrides. They only have Si−H and Si−Si single bonds. The bond lengths are 146.0 pm for a Si−H bond and 233 pm for a Si−Si bond. The structures of the silanes are analogues of the alkanes, starting with silane, SiH4, the analogue of methane, continuing with disilane Si2H6, the analogue of ethane, etc. They are mainly of theoretical or academic interest.
Silicon compounds are compounds containing the element silicon (Si). As a carbon group element, silicon often forms compounds in the +4 oxidation state, though many unusual compounds have been discovered that differ from expectations based on its valence electrons, including the silicides and some silanes. Metal silicides, silicon halides, and similar inorganic compounds can be prepared by directly reacting elemental silicon or silicon dioxide with stable metals or with halogens. Silanes, compounds of silicon and hydrogen, are often used as strong reducing agents, and can be prepared from aluminum–silicon alloys and hydrochloric acid.
Whether there is life on Titan, the largest moon of Saturn, is currently an open question and a topic of scientific assessment and research. Titan is far colder than Earth, but of all the places in the Solar System, Titan is the only place besides Earth known to have liquids in the form of rivers, lakes, and seas on its surface. Its thick atmosphere is chemically active and rich in carbon compounds. On the surface there are small and large bodies of both liquid methane and ethane, and it is likely that there is a layer of liquid water under its ice shell. Some scientists speculate that these liquid mixes may provide prebiotic chemistry for living cells different from those on Earth.
Group 14 hydrides are chemical compounds composed of hydrogen atoms and group 14 atoms.
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