What happens to the attraction of the nucleus for outer electrons as electron shells increase?

As more electron shells are added to an atom, the attraction of the nucleus for the outer electrons generally decreases. This phenomenon is primarily due to the presence of additional inner electron shells that effectively shield the outer electrons from the full positive charge of the nucleus.

In a multi-electron atom, the inner shells create a situation where the outer electrons experience a reduced effective nuclear charge. This shielding effect means that while the outer electrons are still attracted to the nucleus, the strength of that attraction is lessened as the distance from the nucleus increases and more inner shells are present.

Consequently, even though the total positive charge of the nucleus remains the same, the outer electrons feel a reduced pull as they are surrounded by more electron shells. This results in a decrease in the attraction of the nucleus for the outermost electrons as the number of electron shells increases.

Understanding this concept is crucial when studying trends in atomic size, ionization energy, and electron affinity across the periodic table, as the decrease in attraction is a key factor influencing the behavior of atoms.