Atomic Shells and Subshell Designations in GOB Chemistry

Atomic Structure: Shells and Subshells

Introduction to Shells and Subshells

Atoms are composed of electrons arranged in energy levels called shells, which are further divided into subshells (also known as sublevels). Each shell is assigned a principal quantum number (n), and each subshell is designated by a letter (s, p, d, f) that corresponds to the type of orbital present.

Subshell Designations

The table below summarizes the possible subshells for each shell number:

Shell Number (n)	1	2	3	4
Subshell	s	s, p	s, p, d	s, p, d, f

Key Terms and Definitions

• Shell (n): The principal energy level of an atom, indicated by the quantum number n (e.g., n = 1, 2, 3, 4).

• Subshell: A division of a shell, identified by the letters s, p, d, or f, which correspond to different types of atomic orbitals.

• Orbital: A region within a subshell where electrons are most likely to be found.

Examples and Applications

• Example: For an electron in the 3rd energy level (n = 3) and d subshell, the possible values are:

  • n = 3, subshell = d

• Practice Question: Provide the identity of an orbital that is in the fourth shell and has a value of l that is 3.

  • Answer: 4f (since l = 3 corresponds to the f subshell, and n = 4 is the fourth shell)

• Practice Question: How many sublevels are contained in the third shell (n = 3) for a given atom?

  • Answer: 3 (s, p, and d)

Quantum Numbers and Subshells

• The principal quantum number (n) determines the shell.

• The azimuthal quantum number (l) determines the subshell:

  • l = 0: s subshell

  • l = 1: p subshell

  • l = 2: d subshell

  • l = 3: f subshell

Formulas and Equations

• Number of Subshells in a Shell: $\text{Number of subshells} = n$

• Possible values of l: $l = 0, 1, 2, ..., (n-1)$

Summary Table: Shells and Subshells

Shell (n)	Possible Subshells	Values of l
1	s	0
2	s, p	0, 1
3	s, p, d	0, 1, 2
4	s, p, d, f	0, 1, 2, 3

Additional info: The number of subshells in a shell is equal to the value of n, and each subshell contains a specific number of orbitals: s (1), p (3), d (5), f (7).