Atoms & the Periodic Table
Atomic structure and periodic trends.
Atoms
How Electron Configuration Works: A Step-by-Step Guide
Learn how electrons fill orbitals using the Aufbau principle, Pauli exclusion and Hund's rule, with worked examples for common elements.
AtomsWhat Are Isotopes? Atoms of the Same Element with Different Masses
Isotopes share a proton count but differ in neutrons. See how mass number, natural abundance and average atomic mass work, with real examples.