NEET Class neet Answered
The correct order of second ionisation potential of carbon, nitrogen, oxygen, fluorine is:
O>F>N>C.
Nitrogen: [He] 2s2 2p3
Oxygen: [He] 2s2 2p4
Florine: [He] 2s2 2p5
Carbon: [He] 2s2 2p2
After removing one electron:
Nitrogen: [He] 2s2 2p2 - After removal of one more electron, it will have only one electron in its outermost p-subshell.
Oxygen: [He] 2s2 2p3 - After removal of one more electron, it will have two electrons in p-subshell which makes it very unstable.
Also it is difficult to remove electron form stable configuration (half filled). More energy is required to remove electron, so the ionisation potential is very high.
Fluorine: [He] 2s2 2p4 - After removal of one more electron, it will occupy stable half-filled configuration.
Carbon: [He] 2s2 2p1 - After removal of one more electron, it will occupy ideal gas configuration. Hence it will easily give away second electron having very low second IP.