Chapter 5, Problem 30A

Interpretation Introduction

Interpretation: To determine the significance of the boundary of an electron cloud.

Concept Introduction: According to the electron cloud concept, although the precise location of an electron at any given time cannot be determined, certain locations are more likely to contain electrons.

Answer to Problem 30A

The area where an electron would be located $90\%$ of the time is described by the boundary of an electron cloud.

Explanation of Solution

The boundary of an electron cloud would be essential because it indicates where the electrons are situated within the atom. The cloud model was essentially a history of both the electron's likely past and future locations.

The concept that electrons can only orbit the nucleus at specific distances, or "energy levels," was first proposed by Bohr. The energy of electrons increases with distance from the nucleus. A model of an electron cloud serves as an electron's representation today.