Podcast
Questions and Answers
Which of the following statements accurately describes the shielding effect?
Which of the following statements accurately describes the shielding effect?
- Electrons in the same subshell provide significant shielding to one another.
- Core electrons are most effective at shielding valence electrons from the nuclear charge. (correct)
- Valence electrons are most effective at shielding core electrons from the nuclear charge.
- Electrons in higher energy subshells provide significant shielding to lower energy subshells.
According to the concept of effective nuclear charge, electrons in the same subshell effectively shield each other from the full nuclear charge.
According to the concept of effective nuclear charge, electrons in the same subshell effectively shield each other from the full nuclear charge.
False (B)
State the general trend in effective nuclear charge ($Z_{eff}$) across a period (from left to right) on the periodic table.
State the general trend in effective nuclear charge ($Z_{eff}$) across a period (from left to right) on the periodic table.
increases
Slater's rules are used to calculate the ______ nuclear charge.
Slater's rules are used to calculate the ______ nuclear charge.
Which type of electron is most effective at shielding valence electrons?
Which type of electron is most effective at shielding valence electrons?
How do 3_s_ electrons affect 3_p_ electrons?
How do 3_s_ electrons affect 3_p_ electrons?
In Slater's rules, what value is assigned to the shielding constant for each electron added if it is in the same group?
In Slater's rules, what value is assigned to the shielding constant for each electron added if it is in the same group?
According to shielding effect principles, a 3_p_ electron provides significant shielding to a 3_s_ electron.
According to shielding effect principles, a 3_p_ electron provides significant shielding to a 3_s_ electron.
Which of the following factors primarily determines the energy of an electron in a multi-electron atom?
Which of the following factors primarily determines the energy of an electron in a multi-electron atom?
For a given principal quantum number (n), an electron in a d orbital generally experiences greater penetration and thus less shielding than an electron in an s orbital.
For a given principal quantum number (n), an electron in a d orbital generally experiences greater penetration and thus less shielding than an electron in an s orbital.
What happens to the energy levels of subshells within a given electron shell in multi-electron atoms compared to hydrogen atoms?
What happens to the energy levels of subshells within a given electron shell in multi-electron atoms compared to hydrogen atoms?
As the number of angular nodes for an electron increases, its access to the nucleus and thus its attraction to the nucleus generally __________.
As the number of angular nodes for an electron increases, its access to the nucleus and thus its attraction to the nucleus generally __________.
Which of the following statements accurately describes the relationship between orbital shape and penetration?
Which of the following statements accurately describes the relationship between orbital shape and penetration?
The effective nuclear charge ($Z_{eff}$) experienced by an electron is always equal to the actual nuclear charge (Z).
The effective nuclear charge ($Z_{eff}$) experienced by an electron is always equal to the actual nuclear charge (Z).
How does the penetration ability of an electron affect its shielding effect on other electrons?
How does the penetration ability of an electron affect its shielding effect on other electrons?
Match the following orbitals to their appropriate penetration strength relative to the nucleus:
Match the following orbitals to their appropriate penetration strength relative to the nucleus:
Which of the following electron configurations is expected based on the Aufbau principle but is actually different due to increased stability from having half-filled or fully filled d orbitals?
Which of the following electron configurations is expected based on the Aufbau principle but is actually different due to increased stability from having half-filled or fully filled d orbitals?
Increasing the charge of a metal ion by ionization decreases the energy of the δ orbitals relative to the (δ + 1) orbitals due to increased nuclear penetration.
Increasing the charge of a metal ion by ionization decreases the energy of the δ orbitals relative to the (δ + 1) orbitals due to increased nuclear penetration.
What rule is used to determine the lowest energy arrangement of electrons in a subshell, specifically stating that electrons will individually occupy each orbital before doubling up in any one orbital?
What rule is used to determine the lowest energy arrangement of electrons in a subshell, specifically stating that electrons will individually occupy each orbital before doubling up in any one orbital?
The actual electron configuration of Copper is [Ar]4s¹3d¹⁰ instead of the expected [Ar]4s²3d⁹, this deviation increases the _________ of the electronic configuration.
The actual electron configuration of Copper is [Ar]4s¹3d¹⁰ instead of the expected [Ar]4s²3d⁹, this deviation increases the _________ of the electronic configuration.
Which element's electron configuration is an exception to the Aufbau principle, similar to Chromium (Cr) and Copper (Cu)?
Which element's electron configuration is an exception to the Aufbau principle, similar to Chromium (Cr) and Copper (Cu)?
An orbital diagram must include all orbitals in a subshell, even if some orbitals are unoccupied.
An orbital diagram must include all orbitals in a subshell, even if some orbitals are unoccupied.
What causes the energy difference between the orbitals, leading to some subshells being filled before others?
What causes the energy difference between the orbitals, leading to some subshells being filled before others?
Match the element with their valence configuration:
Match the element with their valence configuration:
Flashcards
What does '#' represent in context of core electrons?
What does '#' represent in context of core electrons?
The number of core electrons.
What are Slater's Rules used for?
What are Slater's Rules used for?
Using specific rules to calculate effective nuclear charge.
What is the Screening (Shielding) Effect?
What is the Screening (Shielding) Effect?
The reduction of the attractive force between the nucleus and valence electrons due to core electrons.
Which electrons best shield valence electrons?
Which electrons best shield valence electrons?
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Shielding between subshells?
Shielding between subshells?
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Do electrons within the same subshell shield each other?
Do electrons within the same subshell shield each other?
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What is the purpose of the term 'u'?
What is the purpose of the term 'u'?
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What does 'e-' refer to?
What does 'e-' refer to?
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Subshell Degeneracy
Subshell Degeneracy
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Energy and 'n'
Energy and 'n'
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Energy and 'l'
Energy and 'l'
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Orbital Shape Impact
Orbital Shape Impact
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Effect of Angular Nodes
Effect of Angular Nodes
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Penetration and Shielding
Penetration and Shielding
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S-orbital Penetration
S-orbital Penetration
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P & D Orbital Penetration
P & D Orbital Penetration
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Hund's Rule
Hund's Rule
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Electron Configuration Exceptions
Electron Configuration Exceptions
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Chromium Configuration
Chromium Configuration
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Copper Configuration
Copper Configuration
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Effect of Ionization
Effect of Ionization
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Orbital Diagram
Orbital Diagram
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Orbital Representation
Orbital Representation
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Complete Orbital Diagram
Complete Orbital Diagram
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Study Notes
- This covers electron configurations, effective nuclear charge, and related concepts.
Energy Levels in the Hydrogen Atom
- The energy of each shell is determined solely by the principal quantum number "n".
- This holds true for all 1-electron systems.
- Subshells (s, p, d...) within the same shell are degenerate, meaning they have the same energy.
- The equation for the energy of an orbital is En = -RhZ²/n², where:
- En is the energy of the orbital.
- h is Planck's constant.
- Z is the nuclear charge.
- R is Rydberg's constant.
- n is the principal quantum number.
Energy of Orbitals in Non-Hydrogen Atoms
- Energy levels are split and subshells are no longer degenerate.
- Energy increases as n increases, meaning electrons are further away from the nucleus.
Orbital Energy as a Function of Shape (Penetration Ability)
- The energy of orbitals increases as l increases.
- The shape significantly impacts its penetrating ability.
- Angular nodes reduce an electron's access to the nucleus / its attraction.
- Penetration of electrons into the inner shell reduces the magnitude of shielding they experience, and increases their ability to shield other electrons.
- S-orbitals have significant penetration, but it's attenuated for p and d-orbitals.
Effective Nuclear Charge
- Z, the nuclear charge, is the number of protons in the nucleus.
- Zeff is the actual magnitude of the positive charge "experienced" by an electron in an atom.
- Electrons are simultaneously attracted to the nucleus but repelled by one another.
- Shielding (or screening) is the partial obstruction of nuclear charge by other electrons.
- Zeff = Z - σ, where σ is the shielding constant
- To estimate σ, count the number of core electrons
- "Slater's rules" can be used to calculate σ more specifically and accurately.
Screening (Shielding) Effectiveness
- Core electrons are most effective at shielding valence electrons.
- Electrons in a lower of the same subshell type provide very effective shielding.
- Electrons in the same shell but different subshell types are less effective at shielding one another.
- Lower energy subshells provide some shielding to higher energy subshells.
- Electrons within the same subshell do not shield one another.
Electron Configurations
- An electron configuration lists an atom's occupied atomic orbitals and the number of electrons in each, as described by the quantum numbers (n, l, ml, and ms).
- Electrons are listed from lowest to highest energy.
- This notation defines the atom's chemical and physical properties.
- There ar three primary arrangement principles:
- Aufbau principle: place electrons in the lowest energy orbitals first
- Pauli exclusion principle: no two electrons can have the same four quantum members and the maximum is 2 e- per orbital (+1/2, -1/2...↑↓)
- Hund's rule = The most stable degenerate orbitals arrangement is the one in which parallel spins are maximized
Periodic Table Coordinate System
- Orbitals in the nth period are filled from left to right, in order: ns, (n-2)f, (n-1)d, np
Writing Electron Configurations
- Practice configurations
- Magnesium (Z = 12): 1s² 2s² 2p⁶ 3s²
- Selenium (Z = 34): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴
- Tantalum (Z = 73): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d³
Writing Noble Gas Electron Configurations
- A noble gas configuration is a simplified configuration that includes [noble gas] in the preceding row, followed by remaining e- configuration.
- The e- up to the noble gas are core, and don't participate in bonding.
- The e- outside of the noble gas core are generally valence e-, and do participate in bonding
- For main group elements, valence e¯ = outermost s and p e¯(s and p block)
- For d-block elements, valence e¯ = outermost s and d e
- Example configurations
- Silicon (Z=14):[Ne] 3s² 3p²
- Germanium (Z=32):: [Ar] 4s² 3d¹⁰ 4p²
- Nickel (Z=28): [Ar] 4s² 3d⁸
- Tantalum (Z = 73): [Xe ] 6s² 4f¹⁴ 5d³
Common Exceptions in Electron Configurations
- Exceptions in electron configurations are common in the transition metals and lanthanides/actinides.
- Apparent results: "special stability of half-filled subshells" are due to similarity of orbital energies for 4s/3d, 5s/4d, etc., minimizing repulsions and maximizing parallel spins
- Also due to shielding (Slater's rules).
- Exceptions to recognize: Cr, Mo, Cu, Ag, Au
- Chromium
- expected: [Ar]4s² 3d⁴
- reality: [Ar] 4s¹ 3d⁵
- Copper
- expected: [Ar]4s² 3d⁹
- reality: [Ar] 4s¹ 3d¹⁰
Orbital Diagram Notation
- Shows orbital diagrams for elements like Li, O, P, and Fe.
Describing and Utilizing the Periodic Table
- Periods = rows, Groups (families) = columns
- Analogous valence e- configurations lead to similar periodic properties
- Some families are referred to by common names
- Main group elements tend to gain, lose or share the number of valence electrons needed to achieve the same number of electrons as the nearest noble gas
- Common charges can be predicted by group #
- Groups 1A-3A charges = group # (cation)
- Groups 5A-7A charges = group # - 8 (anion)
Electron Configurations for Main Group Ions
- Ion = a non-neutral atom; an atom that has lost or gained valence e
- Cation = a positive ion, where: #p⁺ > # e⁻
- Anion = a negative ion, where: #p⁺ < # e⁻
- Writing electron configurations for main group (s- and p-block) ions:
- Write the e- configuration of the neutral element
- Cation: remove e- from the highest energy valence orbital(s)
- Anion: add e- to the lowest energy available orbital(s)
- Example configurations
- Na (neutral): 1s²2s²2p⁶3s¹
- Na⁺ (ion): 1s² 2s² 2p⁶ (isoelectronic with Ne)
- F (neutral): 1s²2s²2p⁵
- F⁻ (ion): 1s² 2s² 2p⁶
Electron Configurations for Transition Metal Ions
- For transition metal (d-block) ions, write the e configuration of the neutral element.
- Cation: remove e from highest "n" orbital first
- Anion: add eto "lowest e available orbitals first
- For any transition metal ion (oxidation state > 0), the (n)s subshell is higher in energy than the (n - 1)d subshell
- Why electrons are removed from the "4s" before the "3d"
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Description
Test your knowledge of the shielding effect and effective nuclear charge. Explore Slater's rules, trends across the periodic table, and the impact of different electron types on shielding. Dive deep into electron energy and penetration in multi-electron atoms.
