Subshells, orbitals

The electronic configuration of an atom describes the number of electrons that an atom possesses, and the orbitals in which these electrons are placed. The arrangements of electrons in orbitals, subshells and shells are called electronic configurations. Electronic configurations can be represented by using noble gas symbols to show some of the inner electrons, or by using Lewis structures in which the valence electrons are represented by dots. 

This means that there is only one orbital, which is the s orbital in the first shell. Since 1 =0, the only acceptable m, value for the s orbital subshell is also 0... 

Figure 5-31 A periodic table colored to show the kinds of atomic orbitals (subshells) being filled and the symbols of blocks of elements. The electronic structures of the A group elements are quite regular and can be predicted from their positions in the periodic table, but many exceptions occur in the d and/blocks. The colors in this figure are the same as those in Figure 5-28.

This shows that the nitrogen atom has a nuclear charge of +7, and it therefore has seven electrons. Two electrons are in the first main shell in an r orbital, and the other five are in the second main shell, two in the r orbital and three in the p, py, and p orbitals. Each can have as many kinds of orbitals (subshells) as the shell number. The first shell has one (r), the second has two (r and p), the third has three (r, p, and d), and the fourth has four... 

An s orbital is spherical in shape. All p orbitals have dumbbell shape with two lobes aligned along an axis (see page 47). All d orbitals have slightly complex shapes (see page 48) and are beyond the scope of our discussion. Each orbital can accomodate a maximum of two electrons. Hence, an s subshell, (only one orbital) can accomodate a maximum of two electrons. Similarly, p (three orbitals), d (five orbitals), and/(seven orbitals) subshells can have maximum of six, ten, and fourteen electrons, respectively. 

Figure 3-5 is a blank energy level diagram you can use to depict electrons for any particular atom. Not all the known orbitals and subshells are shown. But with this diagram, you should be able to do most anything you need to. (If you don t have a clue what orbitals, subshells, or all those numbers and letters in the figure have to do with the price of beans, check out the Quantum mechanical model section, earlier in this chapter. Fun read, lemme tell ya.)... 

Fig. 6.1. Orbital subshell energy levels allow the chemist to figure out bonding of elements.

Additionally, just as opposites charges attract and like charges repel, so it is with pairs of electrons in orbital subshells. Two electrons at the same energy level cannot be placed in orbitals together. If one electron is positive, then the other must be negative. 

Determine the number of electrons in designated atomic orbitals, subshells, or shells. (Section 3.2)... 

The arrangement of electrons into orbitals, subshells, and shells provides an explanation for the similarities in chemical properties of various elements, h Table 3.2 gives the number of electrons in each shell for the first 20 elements of the periodic table. 

A new concept is often made easier to understand by relating it to something familiar. The concept of electronic configurations is very likely new to you, but you are probably familiar with hotels. The way electrons fill up orbitals, subshells, and shells around a nucleus can be compared to the way rooms, floors, and hotels located near a convention center will fill with convention delegates. To make our analogy work, imagine that the hotels are located on a street that runs uphill from the convention center, as shown. Further imagine that none of the hotels has elevators, so the only way to get to upper floors is to climb the stairs. 

The d-block transition metals/elements are considered those elements that have, as their name suggests, the d-orbital subshells partly occupied in either the neutral atom or ionic state (lUPAC 2004). Accordingly, the following metals can be included in this group ... 

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