Humber Admissions Practice Test

What does electron configuration refer to in atomic structure?

1. The total energy of an atom

2. The arrangement of electrons in an atom

3. The mass of an atom

4. The number of protons in the nucleus

The correct answer is: The arrangement of electrons in an atom

Electron configuration refers specifically to the arrangement of electrons in an atom. This arrangement is significant because it helps determine the chemical properties and reactivity of the element. Electrons occupy specific energy levels or orbitals, and their arrangement follows certain rules, such as the Aufbau principle, Hund's rule, and the Pauli exclusion principle. Understanding electron configuration is essential for predictions related to bonding, ionization energy, and the overall stability of an atom. For example, elements with a full outer electron shell tend to be more stable and less reactive, while elements with incomplete shells are more likely to participate in chemical reactions to achieve stability. In essence, when one refers to electron configuration, they are discussing the specific distribution of electrons across various energy levels and orbitals, which is foundational to the study of chemistry and atomic theory.