Electron shielding refers to the blocking of valence shell electron attraction by the nucleus, due to the presence of inner-shell electrons. Electrons in an s orbital can shield p electrons at the same energy level because of the spherical shape of the s orbital.

Where are shielding electrons found?

Electrons in an atom can shield each other from the pull of the nucleus. This effect, called the shielding effect, describes the decrease in attraction between an electron and the nucleus in any atom with more than one electron shell.

Does electron shielding increase from top to bottom?

The ionization energy of the elements within a group generally decreases from top to bottom. This is due to electron shielding. The noble gases possess very high ionization energies because of their full valence shells as indicated in the graph. Note that helium has the highest ionization energy of all the elements.