Ground state electronic configuration hydrogen

Refer to the sets of quantum numbers for hydrogen and helium that you saw earlier. Then use the quantum numbers for lithium to infer why a lithium atom has the ground state electron configuration that it does. 

Hydrogen Hydrogen has only one electron, which must go into the lowest-energy, Is orbital. Thus, we say that the ground-state electron configuration of hydrogen is Is1, where the superscript indicates the number of electrons in the specified orbital. 

The leftmost carbon atom in the structure is sp hybridized, and the other two carbon atoms are sp hybridized. The atoms in the molecule are located on a single straight line, with the exception of the three hydrogen atoms on the leftmost carbon atom, which point outward toward three of the vertices of a tetrahedron. There is a cr bond between each pair of bonded atoms. The p and py orbitals on carbon atoms 2 and 3 combine to form two TT orbitals and two rr orbitals only the former are occupied in the ground-state electron configuration. 

Water. The oxygen-atom ground-state electron configuration is l 2s 2p with an unpaired electron in each of the AOs 2py and 2p. We thus assume that these AOs along with the hydrogen Is AOs will form electron-pair bonds. The three possible ways of pairing these four AOs to get covalent structures are shown in Hg. 15.18. 

The ground state electronic configuration of allyl radical is Pi -HOMO ( Pi) of this radical has opposite sign on the terminal lobes (Ci symmetry). Suprafacial [1,3] hydrogen shift under thermal condition is forbidden because there is no question of inversion at this atom, which is bonded to the carbon atom through its spherically symmetrical Ir-orbital. Antarafacial [1,3] hydrogen shift is allowed only by the principles of orbital symmetry. The transition state is a highly contorted species and the reaction is forbidden because of the steric inhibition involved in such a process. 

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