Final answer:
Electron shielding refers to the blocking of valence shell electron attraction by the nucleus, due to the presence of inner-shell electrons. Shielding is determined by the probability of another electron being between the electron of interest and the nucleus, as well as by the electron-electron repulsions the electron of interest encounters. This results in the effective nuclear charge (Zeff) experienced by electrons increasing as we move from left to right across a period in the periodic table.
Step-by-step explanation:
Electron shielding refers to the blocking of valence shell electron attraction by the nucleus, due to the presence of inner-shell electrons. Shielding is determined by the probability of another electron being between the electron of interest and the nucleus, as well as by the electron-electron repulsions the electron of interest encounters.
Core electrons are adept at shielding, while electrons in the same valence shell do not block the nuclear attraction experienced by each other as efficiently. This results in the effective nuclear charge (Zeff) experienced by electrons increasing as we move from left to right across a period in the periodic table.
An example of electron shielding can be observed when comparing the size of covalent radii. When electrons on the right side of the periodic table experience a stronger pull from the higher effective nuclear charge, they are drawn closer to the nucleus, leading to smaller covalent radii.