How do energy levels differ from electron shells?

Energy levels refer to the potential energy of electrons, while electron shells are physical spaces where electrons reside.

Energy levels and electron shells are two fundamental concepts in atomic structure, but they represent different aspects of an atom's electron configuration. Energy levels, also known as principal energy levels or quantum numbers, are a theoretical construct that describes the potential energy of an electron in an atom. They are often represented by the numbers 1, 2, 3, etc., and each energy level can hold a certain number of electrons. The higher the energy level, the more energy the electron has and the further it is from the nucleus.

On the other hand, electron shells, also known as atomic orbitals, are the physical spaces where these electrons are most likely to be found. Each shell is associated with a particular energy level and is further divided into subshells (s, p, d, f), which are then divided into orbitals. Each orbital can hold a maximum of two electrons. The shape and size of these orbitals vary, with s orbitals being spherical, p orbitals being dumbbell-shaped, and d and f orbitals having more complex shapes.

While both energy levels and electron shells are related to the arrangement of electrons in an atom, they are not the same thing. Energy levels are more about the energy of the electrons, while electron shells are about their physical location. For example, electrons in the first energy level (n=1) are in the first shell, those in the second energy level (n=2) are in the second shell, and so on. However, within each shell, electrons can be in different energy states depending on their subshell and orbital.

In summary, energy levels and electron shells are two different ways of understanding the behaviour and arrangement of electrons in an atom. Energy levels describe the potential energy of electrons, indicating their relative distance from the nucleus and their energy state. Electron shells, on the other hand, describe the physical spaces where these electrons are likely to be found, providing a spatial representation of the atom's electron configuration.