8 Questions
What is the primary principle that determines the order in which electrons occupy orbitals in an atom?
Aufbau Principle
Why do transition metals have more complex electron configurations?
Incomplete d subshells
What is the trend in atomic radius across a period?
Decreases
What is the shorthand notation for electron configuration?
1s² 2s² 2p⁶...
Why do some elements have anomalous electron configurations?
Due to the relative energies of d and s orbitals
What is the principle that states no two electrons in an atom can have the same set of quantum numbers?
Pauli's Exclusion Principle
What is the reason for some elements having more stable electron configurations when subshells are half-filled or fully filled?
Stability of half-filled and fully filled subshells
What is the trend in ionization energy across a period?
Increases
Study Notes
Electron Configuration
Definition
- Electron configuration is the arrangement of electrons in an atom's energy levels or orbitals.
Rules for Electron Configuration
- Aufbau Principle: Electrons occupy the lowest available energy levels.
- Pauli's Exclusion Principle: No two electrons in an atom can have the same set of quantum numbers (n, l, m, s).
- Hund's Rule: When filling degenerate orbitals, electrons occupy each orbital singly before pairing up.
Electron Configuration Notation
- Shorthand Notation: 1s² 2s² 2p⁶ ... (number of electrons in each orbital)
- Box Diagram: orbitals are represented as boxes, with electrons represented by arrows (↑ for +1/2 spin, ↓ for -1/2 spin)
Electron Configuration of Atoms
- First 20 Elements: Follow a regular pattern, with electrons filling orbitals in order of increasing energy.
- Transition Metals: Electron configuration is more complex, with incomplete d subshells.
- Lanthanides and Actinides: Electron configuration is even more complex, with incomplete f subshells.
Electron Configuration and Periodic Trends
- Atomic Radius: Decreases across a period, increases down a group due to electron configuration.
- Electronegativity: Increases across a period, decreases down a group due to electron configuration.
- Ionization Energy: Increases across a period, decreases down a group due to electron configuration.
Exceptions to Electron Configuration Rules
- Half-Filled and Fully Filled Subshells: Some elements have more stable electron configurations when subshells are half-filled or fully filled.
- d-Block Elements: Some elements have anomalous electron configurations due to the relative energies of d and s orbitals.
Electron Configuration
Definition
- Electron configuration is the arrangement of electrons in an atom's energy levels or orbitals.
Rules for Electron Configuration
- Aufbau Principle: Electrons occupy the lowest available energy levels.
- Pauli's Exclusion Principle: No two electrons in an atom can have the same set of quantum numbers (n, l, m, s).
- Hund's Rule: When filling degenerate orbitals, electrons occupy each orbital singly before pairing up.
Electron Configuration Notation
- Shorthand Notation: 1s² 2s² 2p⁶...(number of electrons in each orbital).
- Box Diagram: orbitals are represented as boxes, with electrons represented by arrows (↑ for +1/2 spin, ↓ for -1/2 spin).
Electron Configuration of Atoms
- First 20 Elements: Follow a regular pattern, with electrons filling orbitals in order of increasing energy.
- Transition Metals: Electron configuration is more complex, with incomplete d subshells.
- Lanthanides and Actinides: Electron configuration is even more complex, with incomplete f subshells.
Electron Configuration and Periodic Trends
- Atomic Radius: Decreases across a period, increases down a group due to electron configuration.
- Electronegativity: Increases across a period, decreases down a group due to electron configuration.
- Ionization Energy: Increases across a period, decreases down a group due to electron configuration.
Exceptions to Electron Configuration Rules
- Half-Filled and Fully Filled Subshells: Some elements have more stable electron configurations when subshells are half-filled or fully filled.
- d-Block Elements: Some elements have anomalous electron configurations due to the relative energies of d and s orbitals.
Learn the principles of electron configuration including the Aufbau Principle, Pauli's Exclusion Principle, and Hund's Rule. Understand how electrons occupy energy levels and orbitals in an atom.
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