Unit 3: Atomic Models and Electron Configurations

These flashcards cover key concepts from atomic models, including historic models, principles of electron configurations, and rules governing orbital filling.

Dalton's Atomic Model

Proposed in 1803; described the atom as indivisible, a hard round solid mass like a marble.

Thomson's Model (1907)

Introduced charged particles (proton +, electron -); known for the plum pudding model of the atom.

Rutherford's Gold Foil Experiment

Conducted in 1911; led to the discovery of the nucleus and the nuclear atom, which is mostly empty space with mass concentrated in the center.

Bohr Model (1913)

Described atoms as having fixed pathways for electrons (energy levels) akin to rungs of a ladder, where energy is required for quantum jumps.

Quantum Mechanical Model (1926)

Developed by Schrodinger; describes the behavior and energy of electrons in terms of probability clouds rather than fixed paths.

Atomic Orbitals

Regions within an atom where an electron is likely to be found, described by principal quantum numbers.

Principle Quantum Number (n)

Indicates the principal energy level of an electron in an atom; determines the number of sublevels and orbitals.

Aufbau Principle

Rule stating that electrons fill the lowest energy orbitals first before filling higher energy orbitals.

Pauli Exclusion Principle

States that a maximum of two electrons can occupy a single orbital, and they must have opposite spins.

Hund's Rule

States that electrons must occupy degenerate orbitals singly before pairing up in order to maximize unpaired electrons.