Carbon atom, electron configuration

The carbon atom electronic configuration reads as ls 2s 2p. Since the closed shells ls 2s do not contribute anything, we just ignore them. What matters is the configuration 2p. Three orbitals 2p allow for six spinorbitals, occupied by two electrons only. The number of possible Slater determinants is, therefore, = 15. The lowest-energy Slater determinant... 

Symbol Sn atomic number 50 atomic weight 118.69 a Group IV A (Group 14) metaUic element of carbon family electron configuration Kr] 4di°5s25p2 valence states +2, +4 atomic radius 1.41 A electronegativity 1.7 standard electrode potential, E° for Sn2+ -i- 2e Sn is -0.1375 V ten naturally-occurring sta-... 

The term was first used by Van Vleck who explained it thus, referring to carbon in CH4 ...the spins of the four electrons belonging to sp3 were assumed paired with those of the four atoms attached by the carbon. Such a condition of the carbon atom we may conveniently call its valence state. He then showed a calculation which led to the conclusion that The valence state of C has about 7 or 8 more volts of intra-atomic energy than the normal state. This is the energy required to make the C atom acquire a chemically active condition... [1]. Mulliken defines it saying [it is] a certain hypothetical state of interaction of the electrons of an atomic electron configuration and A valence state is an atom state chosen so as to have as nearly as possible the same condition of interaction of the atom s electrons with one another as when the atom is part of a molecule. [2]. 

The minimum basis set (MBS) includes one Slater function for each orbital in the accepted atomic electron configuration. For carbon, then,... 

The double zeta plus polarization (DZ + P) basis set includes one set of functions with higher / value than found in the atomic electron configuration. For carbon, this basis includes Is, Is, 2s, 2s, 2px, 2px, ... 

Coulomb potential felt by a 2p orbital s electron at a point r in the ls 2s 2p 2p configuration description of the carbon atom is ... 

To improve upon die mean-field picture of electronic structure, one must move beyond the singleconfiguration approximation. It is essential to do so to achieve higher accuracy, but it is also important to do so to achieve a conceptually correct view of the chemical electronic structure. Although the picture of configurations in which A electrons occupy A spin orbitals may be familiar and usefiil for systematizing the electronic states of atoms and molecules, these constructs are approximations to the true states of the system. They were introduced when the mean-field approximation was made, and neither orbitals nor configurations can be claimed to describe the proper eigenstates T, . It is thus inconsistent to insist that the carbon atom... 

It also forms compounds known as carbonyls with many metals. The best known is nickel tetracarbonyl, Ni(CO)4, a volatile liquid, clearly covalent. Here, donation of two electrons by each carbon atom brings the nickel valency shell up to that of krypton (28 -E 4 x 2) the structure may be written Ni( <- 0=0)4. (The actual structure is more accurately represented as a resonance hybrid of Ni( <- 0=0)4 and Ni(=C=0)4 with the valency shell of nickel further expanded.) Nickel tetracarbonyl has a tetrahedral configuration,... 

A vexing puzzle m the early days of valence bond theory concerned the fact that methane is CH4 and that the four bonds to carbon are directed toward the corners of a tetrahedron Valence bond theory is based on the overlap of half filled orbitals of the connected atoms but with an electron configuration of s 2s 2p 2py carbon has only two half filled orbitals (Figure 2 8a) How can it have bonds to four hydrogens ... 

If is inferesfing fo nofe fhaf of fhe 5, S, P, P, and farms which arise from two non-equivalent p electrons, as in the s 2s 2p 3p configuration of fhe carbon atom, only 5,... 

Here, even and odd refer to the arithmetic sum over all the electrons and this selection mle is called the Laporte mle. An important result of this is that transitions are forbidden between states arising from the same configuration. For example, of the terms given in Equation (7.18) arising from the configuration of the carbon atom,... 

The ground configuration of benzene is obtained by feeding the six electrons, which were originally in 2p AOs on the carbon atoms (z axis perpendicular to the ring), into the lower energy MOs giving... 

In Section 7.3.1.3 the 71-electron MOs of benzene were obtained by the Hiickel method using only the Ip AOs on the six carbon atoms. The ground configuration is... 

Here, the bonding between carbon atoms is briefly reviewed fuller accounts can be found in many standard chemistry textbooks, e.g., [1]. The carbon atom [ground state electronic configuration (ls )(2s 2px2py)] can form sp sp and sp hybrid bonds as a result of promotion and hybridisation. There are four equivalent 2sp hybrid orbitals that are tetrahedrally oriented about the carbon atom and can form four equivalent tetrahedral a bonds by overlap with orbitals of other atoms. An example is the molecule ethane, CjH, where a Csp -Csp (or C-C) a bond is formed between two C atoms by overlap of sp orbitals, and three Csp -Hls a bonds are formed on each C atom. Fig. 1, Al. 

Caibon has eight electrons in its valence shell in both methane and carbon tetrafluoride. By forming covalent bonds to four other atoms, carbon achieves a stable electron configuration analogous to neon. Each covalent bond in methane and carbon tetrafluoride is quite strong—comparable to the bond between hydrogens in Fl2 in bond dissociation energy. 

With an atomic number of 28, nickel has the electron configuration [Ar]45 34f (ten valence electrons). The 18-electron rule is satisfied by adding to these ten the eight electrons from four carbon monoxide ligands. A useful point to remember about the 18-electron rule when we discuss some reactions of transition-metal complexes is that if the number is less than 18, the metal is considered coordinatively unsaturated and can accept additional ligands. 

We would normally write the electronic ground state electron configuration of a carbon atom as ls-2s 2p-. Despite the intellectual activity that has gone into defining mythical valence states for carbon atoms in different bonding situations, no one would include a d-orbital in the description of ground state carbon. 

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