---
title: "Effective Nuclear Charge — AP Chem Definition & Trends"
description: "Effective nuclear charge (Zeff) is the net positive pull an electron actually feels after shielding. It's the engine behind every periodic trend in AP Chem Unit 1."
canonical: "https://fiveable.me/ap-chem/key-terms/effective-nuclear-charge"
type: "key-term"
subject: "AP Chemistry"
---

# Effective Nuclear Charge — AP Chem Definition & Trends

## Definition

Effective nuclear charge refers to the net positive charge experienced by an electron in a multi-electron atom. It's not the full nuclear charge because some of this charge is shielded by other electrons in the atom.

## Related Study Guides

- [1.7 Periodic Trends](/ap-chem/unit-1/periodic-trends/study-guide/J1NnoL1NHgd6B1dG2UZe)

## Review

### Related Terms

- Shielding Effect: This refers to the decrease in attraction between an electron and the nucleus in any atom with more than one electron shell.
- [Atomic Radius](/ap-chem/key-terms/atomic-radius): This is half the distance between two nuclei of two identical atoms bonded together. It can be affected by both effective nuclear charge and shielding effect.
- [Ionization Energy](/ap-chem/key-terms/ionization-energy): This is the energy required to remove an electron from a gaseous atom or ion. It's directly related to effective nuclear charge - higher effective nuclear charges generally mean higher ionization energies.