What effect does increasing the number of electrons in a shell have on energy levels?

Increasing the number of electrons in a shell directly affects the energy levels of the atom. When more electrons are added to a particular shell, the overall potential energy of the shell increases. This is because electrons repel one another due to their negative charge, leading to a higher energy state as they push apart from each other.

Additionally, the more electrons present, the more complex the interactions become, which can lead to further increases in energy levels as the electrons occupy various subshells and orbitals. This added complexity often results in electrons being at higher energy levels compared to a shell with fewer electrons.

In summary, as the number of electrons in a shell increases, it corresponds to an increase in energy levels due to both electric repulsion among the electrons and the overall effect of their presence in different energy states within the shell.