There are three types of naturally generated carbonisotopeform:twelveC andthirteenC isstable isotope , andfourteenC hasradioactivity, whichhalf lifeAbout 5730 years.Carbon is one of the few elements found since ancient timesCarbon based organismThe most basic element of.
Thermal conductivity：129 W/(m·K)First ionization energy1086.5 kJ/mol secondionization energy2352.6 kJ/mol The third ionization energy is 4620.5 kJ/mol The fourth ionization energy is 6222.7 kJ/mol The fifth ionization energy is 37831 kJ/mol The sixth ionization energy is 47277.0 kJ/mol.
Bonding: The carbon atom is generally tetravalent, which requires four single electrons, butground stateThere are only two single electrons, so hybridization is always necessary when bonding.The most common way of hybridization isSp3 hybrid, 4valence electronFully utilized, distributed in 4 tracks on average, belonging toequivalent hybridization 。
This structure is completely symmetrical and stable after bondingσ bond, and noLone electron pairThe repulsion is very stable.All carbon atoms in diamond are bonded in this hybrid way.alkaneThe carbon atom of is also in this category.
Allcarbon isotopeEach atom of has six protons, butNeutron numberDifferent (from 2 to 16).There are two natural carbonstable isotope : carbon-12（twelveC) Accounting for 98.93% of the earth's carbon, while carbon-13（thirteenC) Accounting for 1.07% of the rest.In organismstwelveCisotopeThe ratio is higher because biochemical reaction will selectively eliminatethirteenC. International Union of Pure and Applied Chemistry, 1961（IUPAC）It was decided to use the carbon-12 isotope as the definition standard of atomic weight unit.nuclear magnetic resonanceWhat is detected isthirteenC。
Carbon-14（fourteenC) It's naturalradio isotope, on earthabundanceIs one part per trillion (0.0000000001%), mainly existing inatmosphereAnd surface mineral deposits, such as peat and othersOrganic matterEtc.Carbon-14 decays β − at 0.158 MeV energy due tohalf lifeIt is only 5730 years old, so this isotope is almost extinct in ancient rocks, but it will be found in the upper atmosphere (lower stratosphere and higher stratospheretroposphere）Middle meridiancosmic raysAnd nitrogen.fourteenThe abundance of C in the atmosphere and organisms is almost conservative, but it decreases regularly after the death of organisms, which isRadiocarbon datingPrinciple of.The dating method can measure carbon containing substances with a time length of less than 40000 years.
There are 15 known isotopes of carbon, includingsurvival time The shortest iseightC，It will conduct proton emission andAlpha decayThe half-life is 1.98739x10 − 21 seconds.isotopenineteenC has a halo effect, that is, its radiusSpecific densityUniform normal sphereNucleusMuch higher.
