The current theory is that an atom’s electrons are 1. static charges in fixed positions around the nucleus. 2. more like waves than particles when localized in an atom. 3. moving about the nucleus like the planets around the sun.

more like waves than particles when localized in an atom.

Explanation:

The most modern model of an atom is quantum mechanical model.

De broglie proved that every particle possess both wave nature and particle nature.When the size of particles become very small,then wave nature increases and becomes more significant.Since electrons are minute particles, they possess significant wave nature.

This concept is used in quantum mechanical model of atom.

the volume increases