Question

In which orbital does an electron in a phosphorus atom experience the greatest effective nuclear charge 1) 1s 2) 2s 3) 2p 4) 3s

Answer 1

Answer: 1s orbital

Explanation:In phosphorus out of 15 electrons two electrons present in 1s orbital(first shell of atom) and which are very close to the nucleus. So nucleus have  more attractions on first shell

More attractions means more effective nuclear charge

one more extra point for the calculation of effective nuclear charge ,the electrons present in atom are considered as three parts :

one is outer electrons

second one is electrons in (n-1) shell

third one is inner electrons

among these three parts inner electrons have more contribution and those values are:

for n electrons (outer electrons) it is 0.35

for n-1 electrons it is 0.85

for all inner electrons it is 1.00

hence 1s orbital experience more effective nuclear charge