Electrons in Atoms & Periodic Trends

Flashcards covering key vocabulary and concepts related to electrons, atomic structures, and periodic trends.

Ground State

The lowest energy level where an electron starts.

Excited State

When an electron moves to a higher energy level after absorbing energy.

Quantum Mechanics

The branch of physics that explains the behavior of very small particles, such as electrons.

Heisenberg Uncertainty Principle

You cannot simultaneously determine both the position and momentum of an electron.

Ernest Rutherford's Model

The atomic model that proposed a dense positive nucleus with electrons moving around it.

Niels Bohr's Model

Model describing electrons moving in specific circular orbits at different energy levels.

Quantum Mechanical Model

Model that describes electrons as occupying 'electron clouds' where their position is probabilistic.

Aufbau Principle

Electrons fill the lowest energy orbitals first.

Pauli Exclusion Principle

No more than two electrons can occupy a single orbital, and they must have opposite spins.

Hund's Rule

Electrons will fill degenerate orbitals singly before pairing up.

Valence Electrons

Electrons in the highest energy level of an atom.

Electron Configuration

The arrangement of electrons in an atom's energy levels and sublevels.

Cations

Positively charged ions that form by losing electrons.

Anions

Negatively charged ions that form by gaining electrons.

Atomic Size

Increases down a group due to additional energy levels and shielding.

Ionization Energy

The energy required to remove an electron from an atom.

Electronegativity

The measure of an atom's ability to attract electrons in a molecule.