Chapter 32: Problem 59
The number of orbitals in 3rd orbit are : (a) 3 . (b) 10 (c) 18 (d) none of these
Short Answer
Expert verified
The number of orbitals in the 3rd orbit is 9; answer is (d) none of these.
Step by step solution
01
Understand the Quantum Number n
The principal quantum number, denoted by \(n\), specifies the energy level or shell of an electron in an atom. For the 3rd energy level, \(n = 3\).
02
Determine Subshells in the 3rd Energy Level
The different subshells in any given energy level \(n\) are determined by the azimuthal quantum number \(l\), which can range from 0 up to \(n-1\). Therefore, the subshells for \(n = 3\) are \(l = 0\) (s), \(l = 1\) (p), and \(l = 2\) (d).
03
Find the Number of Orbitals in Each Subshell
The number of orbitals in a subshell is determined by the magnetic quantum number \(m_l\), which can range from \(-l\) to \(+l\). Consequently: - The s subshell (\(l = 0\)) has 1 orbital.- The p subshell (\(l = 1\)) has 3 orbitals.- The d subshell (\(l = 2\)) has 5 orbitals.
04
Add the Number of Orbitals
Add the number of orbitals in each subshell for \(n = 3\): \[1 \text{ (s) } + 3 \text{ (p) } + 5 \text{ (d) } = 9 \text{ orbitals in total.}\]
05
Compare with Options
None of the given options (3, 10, 18) suggest 9 orbitals. Thus, the correct answer is 'none of these'.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Principal Quantum Number
The principal quantum number, denoted by \( n \), is a fundamental concept in quantum mechanics that defines the energy level or shell of an electron within an atom. It is an integer value that begins at 1 and can theoretically extend to infinity. The value of \( n \) is crucial because it determines the size of the electron cloud; the larger the number, the further the electron is from the nucleus and the more energy it has.
- \( n = 1 \): Closest to the nucleus, also known as the ground state.
- \( n = 2 \): Second energy level, electrons are further out than those in the first shell.
- \( n = 3 \): Third energy level, this is the level in question for determining the number of orbitals available.
Azimuthal Quantum Number
The azimuthal quantum number, represented by \( l \), provides information about the shape and the number of subshells within a given energy level. It ranges from 0 to \( n-1 \). Each value of \( l \) corresponds to a different type of subshell:
For example, at the third energy level (\( n = 3 \)) in the exercise, \( l \) can take on three values: 0, 1, and 2. Consequently, there are s, p, and d subshells available:
- \( l = 0 \): s subshell
- \( l = 1 \): p subshell
- \( l = 2 \): d subshell
For example, at the third energy level (\( n = 3 \)) in the exercise, \( l \) can take on three values: 0, 1, and 2. Consequently, there are s, p, and d subshells available:
- \( l = 0 \): Corresponds to a s subshell with 1 orbital.
- \( l = 1 \): Corresponds to a p subshell with 3 orbitals.
- \( l = 2 \): Corresponds to a d subshell with 5 orbitals.
Magnetic Quantum Number
The magnetic quantum number, denoted by \( m_l \), describes the orientation of an orbital within a subshell. It also determines the number of orbitals within each subshell. The values of \( m_l \) range from \(-l\) to \(+l\), including zero.
The number of orbitals is crucial for understanding the possible electron configurations in an atom. For the 3rd energy level (\( n = 3 \)) discussed in the exercise, the calculation yields:
Summing these, the total number of orbitals is 9. This reinforces the understanding that quantum numbers are key for deciphering atomic structure and electron distribution.
- If \( l = 0 \), then \( m_l = 0 \). This means one orbital for the s subshell.
- If \( l = 1 \), then \( m_l = -1, 0, +1 \). This results in three orbitals for the p subshell.
- If \( l = 2 \), then \( m_l = -2, -1, 0, +1, +2 \). This gives five orbitals for the d subshell.
The number of orbitals is crucial for understanding the possible electron configurations in an atom. For the 3rd energy level (\( n = 3 \)) discussed in the exercise, the calculation yields:
- 1 orbital from s subshell
- 3 orbitals from p subshell
- 5 orbitals from d subshell
Summing these, the total number of orbitals is 9. This reinforces the understanding that quantum numbers are key for deciphering atomic structure and electron distribution.