Nitrogen valence electron configuration

The Lewis symbol for nitrogen, for example, represents the valence electron configuration 2s22pA.12p>112p 1 (see 1), with two electrons paired in a 2s-orbital and three unpaired electrons in different 2p-orbitals. The Lewis symbol is a visual summary of the valence-shell electron configuration of an atom and allows us to see what happens to the electrons when an ion forms. 

The valence-shell configuration of nitrogen is 2s22pjl 2p 2p . The electronic configuration of potassium is ls22s22p63s23p64s. The valence-electron configuration is described by Sd106s . 

The nitrogen atom in ammonia (NH3) forms three covalent bonds. Nitrogen s electronic configuration shows that it has three unpaired valence electrons (Table 1.2), so it does not need to promote an electron to form the three covalent bonds required to achieve an outer shell of eight electrons—that is, to complete its octet. 

Nitrogen, with a valence electron configuration of 2s 2p, can gain three electrons or lose five electrons to obtain an octet. Nitrogen forms many covalent compounds with oxidation states from -3 to +5, as shown in Table 22.4. 

Phosphorus has a valence electron configuration of 3s 3p, similar to that of nitrogen. Phosphorus also forms many compounds with oxidation states ranging from —3 through -I-5. The most stable compounds have the -1-5 oxidation state. 

The number of covalent bonds an atom forms depends on how many additional valence electrons it needs to reach a noble-gas configuration. Hydrogen has one valence electron (Is) and needs one more to reach the helium configuration (Is2), so it forms one bond. Carbon has four valence electrons (2s2 2p2) and needs four more to reach the neon configuration (2s2 2p6), so it forms four bonds. Nitrogen has five valence electrons (2s2 2p3), needs three more, and forms three bonds oxygen has six valence electrons (2s2 2p4), needs two more, and forms two bonds and the halogens have seven valence electrons, need one more, and form one bond. 

Next, we need to distribute the remaining electrons to achieve a noble gas electron configuration for each atom. Since four electrons were used to form the two covalent single bonds, fourteen electrons remain to be distributed. By convention, the valence shells for the terminal atoms are filled first. If we follow this convention, we can close the valence shells for both the nitrogen and the chlorine atoms with twelve electrons. 

The electron configuration of nitrogen ls22s22p3 shows that there are five valence electrons. Three of them are unpaired in this state so nitrogen can form three bonds, however, hybridization still occurs, with the s and p orbitals mixing to form four sp3 hybrid orbitals. 

Nitrenium ions are isoelectronic to carbenes [177]. They contain a dicoordinated nitrogen atom formally with two valence electrons. The possible electronic structures of the parent nitrenium ion NHj are shown in Figure 7.9. On the basis of Hiickel MO theory one would expect that the lowest energy configuration, that is, the electronic ground... 

It will pay you to know (without having to look in the periodic table or tables of electron configurations) that the halogens (F, Cl, Br, I, At) all have seven valence electrons, that the oxygen family (O, S, Se, Te) all have six, that the nitrogen family (N, P, As) have five, that the carbon family (C, Si) have four, and that the boron family (B) have three It will also pay you to know that electronegativities decrease from right to left in a row, or from top to bottom in a column, in the periodic table... 

To form monatomic anions, we add enough electrons to complete the valence shell. For example, nitrogen has five valence electrons (4), so three more electrons are needed to reach a noble-gas configuration, that of neon. Therefore, the ion will be N3" (5). 

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