Kaplan Nursing Entrance Practice Exam 2025 – The All-in-One Guide to Exam Success!

Electrons play a crucial role in energy transfer during chemical reactions. This is primarily because they are involved in the formation and breaking of bonds between atoms. When atoms bond to form molecules, it is the electrons, particularly those in the outermost shell (valence electrons), that are rearranged or exchanged. This shifting of electrons can either release energy or absorb energy, depending on the type of reaction that occurs.

The other options do not accurately describe the primary role of electrons. The atomic mass is determined mostly by protons and neutrons found in the nucleus, not electrons. Electrons are not located in the nucleus, as that is where protons and neutrons reside; instead, they occupy orbitals in various energy levels around the nucleus. While electrons do contribute to the overall structure of an atom, it is primarily the electromagnetic forces that maintain the atom's physical stability, rather than the electrons themselves. Therefore, the emphasis on the role of electrons in energy transfer during chemical reactions is the best descriptor of their role in an atom.