Question

What is a nuclear charge in the periodic table?

Answer 1

Nuclear Charge

• The nuclear charge is the total charge in the nucleus of all the protons.
• The term effective nuclear charge should be used in place of nuclear charge because effective nuclear charge takes into account the behaviour of all electrons whether they constitute the valence shell or are present in the inner shell.

Trends of nuclear charge in the periodic table

• As the number of protons increases, nuclear charge increases.
• Effective nuclear charge, Z_eff is the net positive charge attracting an electron in an atom.
• The formula for calculating Z_eff is Z_eff = Z - S, where Z is the atomic number and S is the number of shielding electrons.
• Effective nuclear charge significantly increases as we move from left to right in main group elements while in the case of d-block elements it significantly increases down the group.
• For example, for the Lithium atom, then Z =3 (atomic number) and S = 1.7.
• So the value of the effective nuclear charge of 2s electron in Lithium atom is 1.3.