Question

Use a periodic table to rank the following elements in decreasing order of first ionization energy: Ca, Ge, As, Se. Enter with no spaces e.g. Ca>Ge>As>Se

Answer 1

sol:-

ionisation energy:- energy require to remove outmost electron from orbital is call ionisation energy.

ionisation energy depends upon following factor :-

• it decreses if shell number or radius of orbital increses
• it increses when Zeff increses
• it is more for half and fully filled orbital
• and for same number of principle quantum number orbital it is as s > p > d > f because of more number of shell

electronic configuration of Ca = [Ar] 4s²

electronic configuration of Ge = [Ar]4s²3d¹⁰4p²

electonic configuration of As = [Ar]4s²3d¹⁰4p³

electronic configuration of Se = [Ar]4s²3d¹⁰4p⁴

first ionisation trend :-

As>Se>Ge>Ca

As > Se becuase of As have half orbital whereas Se doesnot have half filled orbital.