Why this chapter matters
Atomic structure explains why elements behave differently and sets up every later unit on bonding, reactions, and equilibrium.
What you will learn
- Use atomic number, mass number, and isotopic abundance to calculate average atomic mass.
- Write and interpret electron configurations and orbital diagrams.
- Explain periodic trends in radius, ionization energy, and electron affinity using structure.
Lessons in this chapter
- Subatomic particles and isotopesTrack protons, neutrons, and electrons to represent nuclides and ions correctly.
- Electron configurationUse Aufbau, Pauli, and Hund principles to place electrons in orbitals.
- Photoelectron spectroscopy basicsRelate PES peaks to electron shells and relative binding energy.
- Periodic trends from structureUse effective nuclear charge and shielding to justify periodic patterns.
Study task
Given isotope data for two elements, calculate average atomic mass and explain one observed ionization-energy trend with electron structure.
Chapter checkpoint
Element X has isotopes 35X (75.77%) and 37X (24.23%). What is the average atomic mass?
Average mass = (35 x 0.7577) + (37 x 0.2423) = 35.48 amu (to 2 decimal places).