Understanding Electron Spin (8.1.1) Flashcards
• Review of the Schrödinger atom; knowing where the electrons are likely to be makes it possible to understand how atoms form molecules.
• Review of the Schrödinger atom; knowing where the electrons are likely to be makes it possible to understand how atoms form molecules.
• The Pauli exclusion principle indicates that each electron in an atom must have a unique set of quantum numbers describing it.
• The Pauli exclusion principle indicates that each electron in an atom must have a unique set of quantum numbers describing it.
Review of the Schrödinger atom:
• Electrons reside in orbitals.
• Orbitals have characteristic shapes (s, p, d, f).
• Orbitals describe the electron density probability;
the absolute position of an electron cannot be
determined.
• Orbitals describe how the energies of electrons
are quantized.
From Schrödinger, the quantum numbers are the
principle quantum number (n), the angular quantum
number (l), and the magnetic quantum number (ml).
The quantum numbers for both the first and second
electrons in helium are (1,0,0).
The Pauli exclusion principle indicates that each electron
in an atom must have a unique set of quantum numbers
describing it.
How can the first and second electrons of helium have
the same quantum numbers (1,0,0)?
They do not. The two electrons have different spin.
Electron spin is the property of an electron, called up or
down, describing the interaction of the electron with a
magnetic field. The electron spin is represented by the
electron spin quantum number (ms), which has a value
of +1/2 or –1/2.
Review of the Schrödinger atom:
• Electrons reside in orbitals.
• Orbitals have characteristic shapes (s, p, d, f).
• Orbitals describe the electron density probability;
the absolute position of an electron cannot be
determined.
• Orbitals describe how the energies of electrons
are quantized.
From Schrödinger, the quantum numbers are the
principle quantum number (n), the angular quantum
number (l), and the magnetic quantum number (ml).
The quantum numbers for both the first and second
electrons in helium are (1,0,0).
The Pauli exclusion principle indicates that each electron
in an atom must have a unique set of quantum numbers
describing it.
How can the first and second electrons of helium have
the same quantum numbers (1,0,0)?
They do not. The two electrons have different spin.
Electron spin is the property of an electron, called up or
down, describing the interaction of the electron with a
magnetic field. The electron spin is represented by the
electron spin quantum number (ms), which has a value
of +1/2 or –1/2.
Which statement regarding quantum numbers is not correct?
Electrons may have quantum numbers that overlap as long as they are not in the same place at the same time. (B)
What are legitimate values for the spin quantum number, ms?
−½ and +½ (C)
Which of the following is a possible set of quantum numbers for the two electrons of helium?
(1, 0, 0, +1/2) and (1, 0, 0, −1/2) (D)
What is the difference between a 2s orbital and a 2p orbital?
They have different angular momentum quantum numbers. (D)
Stern and Gerlach carried out experiments in which a beam of silver atoms was exposed to a large, homogeneous magnetic field. They found that the beam split into two parts. What did the splitting of the beam of silver atoms mean in terms of electrons and magnetic fields?
Electrons in the silver atoms were influenced by the magnetic field depending on their orientation with regard to the field. (A)
Which of the following best states the Pauli exclusion principle?
Each electron in an atom must have a unique set of quantum numbers describing it. (A)
Which statement about Stern and Gerlach’s experiments with silver atoms is not correct?
The experiments showed that the first three quantum numbers were the same for every electron in a given silver atom. (A)
A great deal of time and effort has been put into trying to locate the electrons in an atom. Why is it important to understand where the electrons are?
Knowing where the electrons are allows prediction and understanding of how atoms come together to form molecules. (B)
Atoms bond through the interaction of electrons. Knowing where the electrons are in an atom allows prediction of how atoms will bond by understanding which electrons are available.
What forces need to be considered in determining where an electron might be in an atom?
The potential energy, the kinetic energy and the repulsion of like-charged particles (C)
The potential energy represents the attraction between the nucleus and an electron; the kinetic energy represents the movement of an electron around the atom, and when another electron is added to an atom, the repulsive forces of the two like-charged particles must also be taken into consideration in determining where an electron might be in an atom.
Which quantum number was not predicted through the Schrödinger equation?
electron spin quantum number (B)
The electron spin quantum number was not predicted through the Schrödinger equation. Electron spin was discovered by Stern and Gerlach’s experiments with streams of silver atoms.
