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Ch 41: Quantum Mechanics II: Atomic Structure
Young & Freedman Calc - University Physics 14th Edition
Young & Freedman Calc14th EditionUniversity PhysicsISBN: 9780321973610Not the one you use?Change textbook
Chapter 41, Problem 7b

Consider an electron in the NN shell. What is the largest orbital angular momentum it could have? Express your answers in terms of \(\hslash\) and in SI units.

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Identify the principal quantum number (n) for the N shell. The N shell corresponds to n = 4.
Recall that the orbital angular momentum quantum number (l) can take integer values from 0 to (n - 1). For n = 4, the possible values of l are 0, 1, 2, and 3. The largest value of l is 3.
The orbital angular momentum (L) is given by the formula: L = √(l(l + 1))ℏ, where ℏ is the reduced Planck's constant (ℏ = 1.0545718 × 10-34 \, \(\text{J·s}\)).
Substitute the largest value of l (l = 3) into the formula: L = √(3(3 + 1))ℏ = √(12)ℏ.
Express the result in terms of ℏ (U) and in SI units (J·s). The largest orbital angular momentum is L = √(12)ℏ, where ℏ is the reduced Planck's constant.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Orbital Angular Momentum

Orbital angular momentum is a measure of the rotational motion of an electron around the nucleus in an atom. It is quantized and can be expressed using the formula L = mvr, where L is the angular momentum, m is the mass of the electron, v is its velocity, and r is the radius of its orbit. For electrons in atomic shells, the angular momentum is also related to the principal quantum number n, with the maximum value given by L = nħ, where ħ is the reduced Planck's constant.
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Principal Quantum Number (n)

The principal quantum number (n) indicates the energy level of an electron in an atom and determines the size and energy of the orbital. It can take positive integer values (1, 2, 3, ...), with higher values corresponding to higher energy levels and larger orbitals. For an electron in the N shell, n equals 4, which influences the maximum possible angular momentum it can possess.
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SI Units and Conversion

SI units are the standard units of measurement used in science, including physics. Angular momentum is typically expressed in joule-seconds (J·s) in SI units. To express the angular momentum of an electron in the N shell in SI units, one must convert the quantized values derived from quantum mechanics into these standard units, ensuring consistency in calculations and comparisons.
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Related Practice
Textbook Question

A photon is emitted when an electron in a three-dimensional cubical box of side length 8.00×10118.00\(\times\)10^{-11} m makes a transition from the nX=2n_X = 2, nY=2n_Y = 2, nZ=1n_Z = 1 state to the nX=1n_X = 1, nY=1n_Y = 1, nZ=1n_Z = 1 state. What is the wavelength of this photon?

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Textbook Question

Consider an electron in the NN shell. What is the largest orbital angular momentum this electron could have in any chosen direction? Express your answers in terms of \(\hslash\) and in SI units.

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Textbook Question

Consider an electron in the NN shell. What is the largest spin angular momentum this electron could have in any chosen direction? Express your answers in terms of \(\hslash\) and in SI units.

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Textbook Question

Consider an electron in the NN shell. What is the smallest orbital angular momentum it could have?

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Textbook Question

Consider an electron in the NN shell. For the electron in part (c), what is the ratio of its spin angular momentum in the zz-direction to its orbital angular momentum in the zz-direction? Note: Part (c) asked for the largest orbital angular momentum this electron could have in any chosen direction.

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Textbook Question

Model a hydrogen atom as an electron in a cubical box with side length LL. Set the value of LL so that the volume of the box equals the volume of a sphere of radius a=5.29×1011a=5.29\(\times\)10^{-11} m, the Bohr radius. Calculate the energy separation between the ground and first excited levels, and compare the result to this energy separation calculated from the Bohr model.

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