Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

What is a valence shell?

1. The innermost energy level of an atom

2. The outermost energy level containing loosely held electrons

3. The total number of electrons in an atom

4. A shell that contains only protons and neutrons

The correct answer is: The outermost energy level containing loosely held electrons

A valence shell refers to the outermost energy level of an atom that contains electrons. These electrons are known as valence electrons, and they play a critical role in chemical bonding and reactivity. The valence shell is significant because it determines how an atom interacts with other atoms; the number of valence electrons influences the type of chemical bonds an atom can form, whether they are ionic or covalent bonds. The correct choice emphasizes that the electrons in the outermost shell are typically less tightly held compared to those in inner shells, making them more available for chemical reactions. Understanding the concept of the valence shell is essential for grasping how elements combine and the principles of chemical behavior.