Answer:
c. main energy level of an electron
Explanation:
An atom can be defined as the smallest unit comprising of matter that forms all chemical elements. Thus, atoms are considered to be the building blocks of matter and as such defines or determines the structure of a chemical element.
Generally, atoms are typically made up of three distinct particles and these includes; protons, neutrons and electrons.
In Chemistry, electrons can be defined as subatomic particles that are negatively charged and as such has a magnitude of -1.
The principal quantum number, denoted by n, represents the main or overall energy level of an electron.
Basically, this property of an electron determines its energy level, as well as its distance from the nucleus of an atom of any chemical element. Also, as the distance of each orbital from the nucleus increases, the energy level increases respectively. Thus, sets of orbitals having the same principal quantum number (n) are generally referred to as an electron shell.
