Atomic Structure Flashcards

Orbitals and Electrons

• Orbitals indicate regions in space where electrons are likely to be found.
• Each orbital can hold a maximum of 2 electrons, categorized into types: s, p, d, and f.
• The 1st energy level contains one 1s orbital capable of holding 2 electrons, with no other orbital types available.
• The 2nd energy level has one 2s and three 2p orbitals (2s, 2px, 2py, 2pz), accommodating up to 8 electrons total.
• The 3rd energy level consists of one 3s, three 3p, and five 3d orbitals, allowing up to 18 electrons.

Sublevels and Shapes

• Sublevel s contains 1 orbital, with a spherical shape.
• Sublevel p has 3 orbitals, shaped like dumbbells.
• Sublevel d consists of 5 unique orbitals, while sublevel f contains 7 orbitals.

Electronic Configurations

• Lithium has the configuration 1s²2s¹.
• Boron is represented as 1s²2s²2p¹.
• Scandium's configuration is 1s²2s²2p⁶3s²3p⁶4s²3d¹.
• Gallium's configuration is 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p¹.
• The configuration for the anion Se²⁻ is 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶.

Orbital Diagrams

• A box or line represents an orbital in diagrams.
• Arrows illustrate electron spins: ↑ for one spin direction and ↓ for the opposite direction.
• Helium's orbital diagram shows two electrons with opposite spins (↑↓), while lithium's shows one paired and one unpaired (↑↓ ↑).

Principles and Exclusions

• The Pauli Exclusion Principle states that an orbital can hold 2 electrons with opposite spins.
• The Aufbau Principle dictates that electrons fill from the lowest to highest energy levels.
• Noble gas configuration starts with a noble gas symbol in brackets, continuing from there for electron configuration.

Ions and Charges

• Cations (positively charged) result from the loss of electrons, while anions (negatively charged) are formed by the gain of electrons.
• The ground state configuration indicates the lowest energy arrangement of electrons.
• Isoelectronic species possess the same number of electrons and thus identical electronic configurations; for example, Ca²⁺ and Argon both share the configuration 1s²2s²2p⁶3s²3p⁶.

Valence Electrons

• Valence electrons can only be lost from the outermost energy levels during ion formation.
• For cation Ca²⁺, the configuration changes after losing 2 electrons, while the anion Se²⁻ gains electrons to fill its outer shell.