Table 5.2 Summary of Atomic Shell, Subshells, and Orbitals for Shells 1–4
SHELL (ENERGY LEVEL) SUBSHELL NUMBER OF ORBITALS ELECTRON CAPACITY
1 s 1 2 total
2s12
p3 6
8 total
3s12
p3 6
d5 10
18 total
4s12
p3 6
d5 10
f7 14
32 total
level 2 (shell 2) has two subshells. The subshells are denoted by the symbols s, p, d, f, etc.
and correspond to differently shaped volumes of space in which the probability of finding
the electrons is high. The electrons in a particular subshell may be distributed among vol-
umes of space of equal energies called orbitals.There is one orbital for an s subshell, three
for a p, five for a d, seven for an f, etc. Only two electrons may occupy an orbital. Table 5.2
summarizes the shells, subshells, and orbitals in an atom. The chapter on Spectroscopy,
Light, and Electrons, Chapter 10 has a discussion of the origin of this system.
Energy-Level Diagrams
The information above can be shown in graph form as an energy-level diagram, as shown
in Figure 5.1:
48 STEP 4. Review the Knowledge You Need to Score High
5p
4p
3p
2p
4d
3d
5s
4s
3s
2s
1s
Figure 5.1 Energy-level diagram of an atom.