Effective Nuclear Charge, Z*

• Z* is the nuclear charge experienced by an electron.

• Z* increases across a period owing to incomplete shielding by inner electrons.

• For VALENCE electrons we estimate Z* as:

• Charge felt by 2s e- in Li Z* = 3 - 2 = 1

Be Z* = 4 - 2 = 2

B Z* = 5 - 2 = 3

and so on!

Z* = [ Z - (no. of inner electrons) ]

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