1) Effective nuclear charge (Zeff) is the nuclear charge actually experienced by an electron of an atom, which depends on the orbital and is less than the actual nuclear charge due to shielding by inner shell electrons. 2) Zeff is calculated using the formula Zeff = Z - σ, where Z is the actual nuclear charge and σ is the shielding constant which accounts for screening of the nuclear charge by inner electrons. 3) Factors that affect Zeff include the size of the atom, total nuclear charge, shielding by inner electrons, and penetration of the outer electron into the charge cloud.

1. Effective nuclear charge
Dr. Mithil Fal Desai
Shree Mallikarjun and Shri Chetan
Manju Desai College Canacona Goa

2. Nuclear Charge
Atom
P
P
PP

3. Effective nuclear charge (Zeff)
Nuclear charge is charge on the
nucleus.
Effective nuclear charge is the
nuclear charge actually experienced
by an electron of an atom.
.

4. Effective nuclear charge (Zeff)
Nucleus
e-
Depends on ‘n’ and ‘l’

5. Atomic number and Nuclear charge (Z)
Orbital 1s 1s 1s, 2s 1s, 2s 1s, 2s, 2p 1s, 2s, 2p 1s, 2s, 2p
n of
valence
shell
1 1 2 2 2 2 2
Z 1 2 3 4 5 6 7
e-ns in
neural
atom
1 2 3 4 5 6 7
Element H He Li Be B C N

6. Zeff = Z – σ
σ is shieling constant
Mathematical expression

7. Factors affecting
• Size of an atom
• The total nuclear charge (Z).
• The Screening and Shielding of the inner shell
electrons and neighboring electrons of the same shell.
• The extent of penetration of outermost electron into
the charge cloud.