Nucleus and Electronic Configuration of the Nitrogen Atom

Note The concepts of quantum number, ground state, electron wave number, ground-state orbitals, and valence are briefly reviewed in Ch. 3, Sec. 2,1. 

The element nitrogen has the symbol N and an atomic number (or Z number) of 7, i.e., the neutral atom has seven protons and seven neutrons in the nucleus and correspondingly seven electrons. The ground-state electronic configuration of these seven electrons is Is ls lp, that is, two electrons are in the K shell (1 ) and five in the L Shell two in the 2s orbital and three in the 2p orbital distributed among the p, Py, and p orbital (the five valence electrons). The three Ip electrons are unpaired with spins parallel as shown in Fig. 10.1. 

Under normal conditions, nitrogen exists as a stable diatomic molecule (N2) formed with all three bonds from each atom pointed toward the other atom.f l Molecular nitrogen has an extremely high heat of dissocia-tion l l 

A photoelectron spectrum of the nitrogen molecule is shown in Fig. 10.2 and the electronic structure is shown in Fig. 10.3.1 H 1 The two 2 orbitals of the nitrogen atoms combine to form the two orbitals indicated as 1 (bonding orbital) and 2 (antibonding orbital). The six Ip orbitals combine to form six orbitals. Of these six, three (marked 3, 4, and 5) are bonding orbitals. The electrons ejected from orbital 1 do not appear in the spectrum of Fig. 10.2 because the light energy used is smaller than the ionization potential of these electrons. 

Note Airow lnclcates drectlon of electron spin 

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