Chemistry Chapter 1.2: Electron Configuration

Study Notes

Electron Configuration

Electron configuration follows the sequence 1s², 2s², 2p⁶, etc., demonstrating the arrangement of electrons in orbitals.

Orbital Structure

S orbitals: 1 orbital, can hold 2 electrons
P orbitals: 3 orbitals, can hold 6 electrons
D orbitals: 5 orbitals, can hold 10 electrons
F orbitals: 7 orbitals, can hold 14 electrons
Each shell can accommodate increasing types and numbers of orbitals as shell numbers increase.

Orbitals and Electrons

Formula for orbital count per shell: n² (n is the shell number).
Maximum electrons per shell formula: 2(n²), reflecting the total possible occupants across all subshells.

Periodic Table and Orbitals

Periodic Table elements increase in atomic number, with each added proton also adding an electron in neutral atoms.
Helium is placed next to hydrogen but behaves like a noble gas, influencing its orbital configuration.

Standard and Noble Gas Configurations

Example for Bromine (Br):
- Standard: 1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4p⁵
- Noble gas: [Ar] 4s², 3d¹⁰, 4p⁵
Alkali metals end with s¹, alkaline earth with s², halogens with p⁵, and noble gases with p⁶.

Electron Configuration Exceptions

Elements like Cu, Ag, Au, Cr, and Mo deviate from predicted configurations for energetic stability.
Copper's configuration: [Ar] 4s¹, 3d¹⁰ instead of 4s², 3d⁹, stabilizing subshells.

Ions and Electron Configuration

Sulfur's configuration: [Ne] 3s², 3p⁴ becomes [Ne] 3s², 3p⁶ for sulfide ion (S²⁻).
Potassium ion (K⁺) loses an electron from the 4s orbital, resulting in [Ar].
Zinc ion (Zn²⁺) removes its 4s electrons, leading to [Ar] 3d¹⁰.

Anions and Cations

Anions are negatively charged ions formed by gaining electrons.
Cations are positively charged ions formed by losing electrons.

Electron Configuration in Excited State

Excited zinc configuration: Zn: [Ar] 4s¹, 3d¹⁰, 6p¹ after absorbing energy to promote electrons.

Ground State vs. Excited State

Ground state represents an atom's lowest energy configuration.
Excited state indicates an atom has absorbed energy, resulting in higher energy levels.

Magnetic Properties

Paramagnetic materials have unpaired electrons and are attracted to magnetic fields.
Diamagnetic materials have all paired electrons, showing slight deflection away from magnetic fields.

Core vs. Valence Electrons

Core electrons are lower energy and not involved in bonding, while valence electrons are involved in chemical reactions.
Valence electron examples: Sulfur has 6, potassium has 1, chromium has 6, bromine has 7, zinc has 2, and copper has around 1.

Description

Test your knowledge on electron configurations and the distribution of electrons in various orbitals. This quiz covers essential concepts such as subshells and the number of electrons and orbitals for each shell. Perfect for students studying Chemistry.