# What is a node when it comes to electron density, waves, and wave functions?

##### 1 Answer

Aug 25, 2016

A **node** is a region of zero electron density. That means you *cannot* find electrons at a node.

Visually, on a wave, it would be the point on the wave where the concavity changes. In other words, it is the *zero-crossing*.

Formally, it is when the wave function is

#psi_("atomic orbital") = 0#

except at zero distance away from the nucleus.