What is the outermost shell of electrons orbiting the nucleus of an atom called?

The outermost shell of electrons that orbit the nucleus of an atom is referred to as the valence shell. This shell plays a critical role in determining the chemical properties of an element, as it contains the valence electrons involved in bonding with other atoms. The valence shell is significant because it is where interactions with other atoms occur, influencing how atoms join together to form molecules or compounds.

The concept of the valence shell relates closely to an atom's stability and reactivity. Atoms strive to achieve a full valence shell, which corresponds to a stable electronic configuration. This drive is the reason behind different elemental behaviors during chemical reactions.

In contrast, the other options, while related to atomic structure, do not specifically denote the outermost shell of electrons. The electron cloud describes the space around the nucleus where electrons are likely to be found, but it does not specify the outermost layer. The nucleus is the central part of the atom where protons and neutrons are located and does not involve electrons. Energy levels represent the quantized levels at which electrons can exist, but they encompass more than just the outermost shell, as they include various layers within the atom. Thus, the valence shell is the term that specifically identifies the outermost