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Questions and Answers
What is the primary shape of an s subshell?
What is the primary shape of an s subshell?
The magnetic quantum number, $m_ ext{ℓ}$, can take on values that range from $-ℓ$ to $+ℓ$ including zero.
The magnetic quantum number, $m_ ext{ℓ}$, can take on values that range from $-ℓ$ to $+ℓ$ including zero.
True
What happens to orbital size as the principal quantum number n increases?
What happens to orbital size as the principal quantum number n increases?
Orbital size increases with increasing n.
The magnetic quantum number for all s orbitals is ______.
The magnetic quantum number for all s orbitals is ______.
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Match the subshells with their corresponding shapes:
Match the subshells with their corresponding shapes:
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What concept did Niels Bohr use to describe an atom?
What concept did Niels Bohr use to describe an atom?
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Electrons can occupy any orbit around the nucleus according to Bohr's model.
Electrons can occupy any orbit around the nucleus according to Bohr's model.
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What is the Rydberg constant value given in the formula?
What is the Rydberg constant value given in the formula?
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The electron can move between different orbits by _______ a photon.
The electron can move between different orbits by _______ a photon.
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Match the following terms with their descriptions:
Match the following terms with their descriptions:
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Which principle is TRUE according to Bohr's postulates?
Which principle is TRUE according to Bohr's postulates?
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Quantum mechanics fully describes the behavior of electrons in atoms according to Bohr's views.
Quantum mechanics fully describes the behavior of electrons in atoms according to Bohr's views.
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According to Bohr, what does an electron require to move to a higher energy level?
According to Bohr, what does an electron require to move to a higher energy level?
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Which topic is NOT covered in Lecture 6?
Which topic is NOT covered in Lecture 6?
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Office hours for Prof. Norris and Brisby are held on Wednesdays.
Office hours for Prof. Norris and Brisby are held on Wednesdays.
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What is the formula for Gibbs free energy mentioned in the lecture?
What is the formula for Gibbs free energy mentioned in the lecture?
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In Lecture 5, the maximum spontaneity for a process is indicated by a negative value of ∆______.
In Lecture 5, the maximum spontaneity for a process is indicated by a negative value of ∆______.
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Which topic covers the concept of electron configurations?
Which topic covers the concept of electron configurations?
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Problem Set 5 is due next week before Exercise #7.
Problem Set 5 is due next week before Exercise #7.
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What is the primary focus of the 2nd Law of Thermodynamics?
What is the primary focus of the 2nd Law of Thermodynamics?
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Which factor favors the spontaneity of the reaction from O3 (g) to O2 (g)?
Which factor favors the spontaneity of the reaction from O3 (g) to O2 (g)?
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Light behaves only like a particle and does not exhibit wave properties.
Light behaves only like a particle and does not exhibit wave properties.
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What parameter of light determines its color?
What parameter of light determines its color?
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The speed of light in vacuum is approximately __________ m/s.
The speed of light in vacuum is approximately __________ m/s.
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Match the following wavelengths with their corresponding colors:
Match the following wavelengths with their corresponding colors:
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Which constant is used to calculate the energy of photons?
Which constant is used to calculate the energy of photons?
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Johann Balmer studied the light emitted by oxygen atoms.
Johann Balmer studied the light emitted by oxygen atoms.
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What is the principle that explains the dual nature of light as both a wave and a particle?
What is the principle that explains the dual nature of light as both a wave and a particle?
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Photons are the discrete amounts of energy that light carries, and their energy can be calculated using the formula __________.
Photons are the discrete amounts of energy that light carries, and their energy can be calculated using the formula __________.
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In which semester is full understanding of quantum mechanics generally covered?
In which semester is full understanding of quantum mechanics generally covered?
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What is the emitted photon energy when an electron relaxes from n=3 to n=1?
What is the emitted photon energy when an electron relaxes from n=3 to n=1?
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The Bohr model can explain stable orbits of electrons.
The Bohr model can explain stable orbits of electrons.
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What does the variable 'n' represent in the energy levels?
What does the variable 'n' represent in the energy levels?
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The energy levels can only be explained for the _____ atom.
The energy levels can only be explained for the _____ atom.
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Match the following quantum numbers with their corresponding definitions:
Match the following quantum numbers with their corresponding definitions:
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What is the energy difference when an electron transitions from n=4 to n=2?
What is the energy difference when an electron transitions from n=4 to n=2?
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The maximum energy levels for electrons are determined by the value of n.
The maximum energy levels for electrons are determined by the value of n.
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What is the wavelength of the emitted photon when the transition occurs?
What is the wavelength of the emitted photon when the transition occurs?
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When an electron transitions from an elevated state to a lower state, it _____ energy.
When an electron transitions from an elevated state to a lower state, it _____ energy.
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Which of the following does NOT limit the Bohr model?
Which of the following does NOT limit the Bohr model?
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What shape do p orbitals (ℓ=1) have?
What shape do p orbitals (ℓ=1) have?
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D orbitals (ℓ=2) have three different orientations.
D orbitals (ℓ=2) have three different orientations.
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What is the spin magnetic quantum number for an electron that is spinning 'up'?
What is the spin magnetic quantum number for an electron that is spinning 'up'?
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The __________ has one electron and can be in the ground or excited state.
The __________ has one electron and can be in the ground or excited state.
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Match the quantum numbers with their descriptions:
Match the quantum numbers with their descriptions:
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Which orbitals share the same energy in the second principal level?
Which orbitals share the same energy in the second principal level?
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Energy of atomic orbitals in hydrogen depends only on the principal quantum number n.
Energy of atomic orbitals in hydrogen depends only on the principal quantum number n.
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How many possible values can mℓ take for d orbitals (ℓ=2)?
How many possible values can mℓ take for d orbitals (ℓ=2)?
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Study Notes
Lecture Announcements
- Lecture 6 topics: The Wave Nature of Light, Quantized Energy and Photons, Line Spectra and the Bohr Model, The Wave Behavior of Matter, Quantum Mechanics and Atomic Orbitals, Representation of Orbitals, Multielectron Atoms, Electron Configurations, Electron Configurations and the Periodic Table, Effective Nuclear Charge, Sizes of Atoms and Ions, Ionization Energy, Electron Affinity.
- Problem Set 5 due before Exercise 6.
- Problem Set 6 posted on Moodle; due before Exercise 7 next week.
- Study Center hours: Wednesdays 18:00-20:00 in ETA F 5
- Office Hours: Prof. Norris and Brisby, Thursdays 17:00-18:00 in LEE P 210.
- No office hours this week.
- Next week's topics: Basic Concepts of Chemical Bonding and Molecular Geometry and Bonding Theories (Brown Ch. 8 and 9).
Review
- In lecture 5, 2nd Law of Thermodynamics was introduced; spontaneous vs. nonspontaneous processes.
- Reversible, irreversible processes.
- Included isothermal processes, entropy and the 2nd Law of Thermodynamics.
- Boltzmann's equation and microstates.
- 3rd Law of Thermodynamics.
- The Gibbs Free Energy equation: G = H – TS.
- Gibbs Free Energy equation at constant T: ΔG = ΔH – TΔS.
- Standard Gibbs free energies.
- Role of temperature.
Importance of Temperature
- Determining spontaneity of a reaction depends on temperature.
- ΔH , ΔS, -TAS and the reaction characteristics at specific temperatures.
- Examples of reactions sensitive to temperature changes (with favorable enthalpy and entropy, etc).
Electronic Structure
- Chemistry involves electrons that determine reactivity among atoms.
- Bonds hold atoms and build molecules.
Light
- Light consists of oscillating electromagnetic waves.
- Important parameters: wavelength (λ), frequency (ν), speed of light (c).
- The speed of light is constant at a value of 2.998x10⁸ m/s.
- Color depends on wavelength: 430 nm is blue, 530 nm is green, 630 nm is red.
- Light carries energy in discrete amounts known as photons.
- Energy of a photon (E) = hν where h is Planck's constant (6.626 x 10⁻³⁴ J⋅s). Alternatively = hc/λ.
Light Emitted from Hydrogen Atoms
- Light sources emit white light.
- Hydrogen atoms emit light at specific energies.
Mystery of Hydrogen
- Hydrogen atom emits photons at certain energies explained by an empirical formula called Rydberg Equation.
- Important entity in the Rydberg equation is the Rydberg constant (R) with a value of 1.097x10⁷ m⁻¹.
Bohr Model
- Atomic-scale solar system analogy.
- Electrons occupy specific orbits with quantized energies (En).
- Electrons move between orbits by absorbing or emitting photons with energy (Eph = hv).
- Equation for change in energy (ΔE) between two electron levels.
Orbital Energies
- Energy levels (En) are calculated using relevant entities
- Electron transitions and photon energy calculations.
Limitations of Bohr Model
- Fails to explain stable orbits of electrons in atoms other than hydrogen.
- Quantum mechanics provides a model to address these limitations.
- Uncertainty principle: The uncertainty in position (Δx), and momentum (Δp), of an electron cannot be simultaneously known. ( Δx. Δp ≥ h/4π.)
- Orbit is fuzzy, thus, referring to the electron cloud model.
Quantum Mechanics
- Quantum mechanics resolves limitations of the Bohr model.
- Explains electron behavior using wavefunctions
- Explains probabilities of finding an electron.
- Describes orbitals by quantum numbers: n, l, ml, and ms
Quantum Numbers
- Orbitals are described by four quantum numbers: n principal quantum number; l angular momentum quantum number; ml magnetic quantum number (between -l and l); ms spin quantum number (+1/2 or -1/2).
- The range of values for l and ml are given with respect to the principal quantum number n.
Summarizing Labels for Atomic Orbitals
- Table summarizing the relationships between n, l, and ml for different electron shells (up to n = 4).
Visualizing Atomic Orbitals
- Graphical representations of orbitals (s, p, and d).
- Illustrate electron cloud concept and probabilities of finding electrons.
Energy of Atomic Orbitals in Hydrogen
- Hydrogen has one electron.
- Energy levels depend only on the value of n (the principal quantum number).
- Identical values of energy for similar subshells.
- Diagrams illustrating energy levels and orbitals
Last Quantum Number?
- Discusses the spin magnetic quantum number(ms).
- It has one two values.
- It describes electron spin and its effect on magnetic fields.
Energy of Atomic Orbitals in Multielectron Atoms
- Multielectron atoms have more than one electron.
- Electrons in multielectron atoms fill atomic orbitals with particular quantum numbers according to their energy in order from lowest to highest.
- Pauli Exclusion Principle: No two electrons in the same atom can have the same set of quantum numbers.
- Electron repulsion between electrons within the same shell.
- Ordering of subshells using periodic table.
Order of Subshells
- Determining the order of filling subshells using the periodic table.
Electron Configurations
- Table summarizing electron configurations for lighter elements (Li, Be, B, C, N, and Ne).
- Illustrating Hund's rule for filling atomic orbitals with respect to electron spin.
Valence Electrons
- Valence electrons are those in the outermost electron shell.
- Noble gas core configuration and valence electron configuration.
- Determining electron configurations using periodic table.
Exceptions
- Exceptions to normal electronic configurations due to electron repulsions.
Screening
- Valence electrons feel less than the full nuclear charge due to repulsion from the core electrons.
- Effective nuclear charge (Zeff) is lower than the nuclear charge (Z).
- Greater distance from the nucleus reduces repulsion, causing the influence of Z to decrease.
Atomic Size
- Methods for defining atomic sizes.
- Trends: increase down a group; decrease across a period.
Ionic Radii
- Estimating ionic sizes from bond lengths in ionic solids.
- Trends: cations smaller than neutral atoms; anions larger than neutral atoms.
- Trends with respect to charge of ion.
Ionization Energy
- Energy needed to remove an electron from an atom.
- Trends: increase across a period; decrease down a group.
- Values of 1st and subsequent ionization energy.
Electron Affinity
- Energy change when an atom gains an electron.
- Trends: generally increase across a period; decrease down a group (except for noble gases).
Summary of Key Concepts
- Key takeaways from the lecture.
- Next topic to be discussed.
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Description
Test your knowledge on quantum mechanics, focusing on the s subshell shapes, magnetic quantum numbers, and Bohr's model of the atom. This quiz covers essential concepts such as orbital size, the Rydberg constant, and electron transitions. Perfect for students studying advanced chemistry and physics.
