Humber Admissions Practice Test

What is the outermost electron shell referred to as?

1. Principal shell

2. Valance shell

3. Core shell

4. Subshell

The correct answer is: Valance shell

The outermost electron shell of an atom is referred to as the valence shell. This term is significant because the electrons in this shell, known as valence electrons, play a crucial role in determining an atom's chemical properties and its ability to bond with other atoms. Atoms seek to achieve a full valence shell, often leading to the formation of chemical bonds during reactions. The concept of the valence shell is important in chemistry as it underpins theories related to electron configuration, reactivity, and the formation of compounds. Understanding which electrons are in the valence shell helps in predicting how an element will interact with others, which is fundamental in fields ranging from organic chemistry to materials science. Other terms mentioned, like "principal shell" and "core shell," refer to different aspects of electron configuration and structure, but they do not specifically denote the outermost shell's importance in chemical bonding and reactivity. A "subshell" refers to a subdivision of shells that can contain multiple orbitals, further detailing electron distribution within a given shell. Thus, the valence shell is the predominant term that encapsulates the significance of the outermost shell in terms of chemistry.