What is zeff?

Zeff is a term used in chemistry that stands for the effective nuclear charge. It refers to the electric charge experienced by an electron in an atom, which takes into account the shielding effect of other electrons in inner shells.

In simpler terms, zeff is the net positive charge that an electron feels from the nucleus of an atom. This is because the negatively charged electrons are attracted to the positively charged protons in the nucleus, but they are also repelled by other negatively charged electrons in the same atom. As a result, this net positive charge affects the behavior of electrons in an atom.

Calculating zeff is important in understanding the chemical properties of an atom, such as its ionization energy, electron affinity, and atomic radius. It varies across different elements and increases from left to right in a period of the periodic table, as the number of protons and electrons increases.