Question

For an atom or mono-atomc ions, which electrons require the least energy to remove?
d electrons
valence electrons
core electrons
f electrons

Answer 1

valence electrons require the least energy to remove for an atom or mono-atomic ions.

The shielding effect explains why valence shell electrons are more easily removed from the atom. The nucleus can pull the valence shell in tighter when the attraction is strong and less tight when the attraction is weakened. The more shielding that occurs, the further the valence shell can spread out. As a result, atoms will be larger.

(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. The more electron shells there are, the greater the shielding effect experienced by the outermost electrons.)