---
title: "Subshells — AP Chem Definition, PES & Electron Configs"
description: "Subshells (s, p, d, f) are the sublevels inside electron shells. In AP Chem, they explain electron configurations and every peak in a PES spectrum."
canonical: "https://fiveable.me/ap-chem/key-terms/subshells"
type: "key-term"
subject: "AP Chemistry"
---

# Subshells — AP Chem Definition, PES & Electron Configs

## Definition

Subshells are a division of electron shells separated by different quantum numbers. They are designated as s, p, d, and f.

## Related Study Guides

- [1.5 Atomic Structure and Electron Configuration](/ap-chem/unit-1/atomic-structure-electron-configurations/study-guide/DiW6kVmwDRDakxKodjw5)
- [1.6 Photoelectron Spectroscopy](/ap-chem/unit-1/photoelectron-spectroscopy/study-guide/Xx7nwanr96Uzt1zSvwRA)

## Review

### Related Terms

- Shell: This is the energy level of an atom where electrons reside. It's like the "room" in our mansion analogy.
- Quantum Numbers: These are values that describe the characteristics of electrons such as their energy level (shell), shape (subshell), orientation in space, and spin direction.
- Orbital: This is a region within an atom where there's a high probability to find an electron. It's like specific spots within our subshell "areas".