Q.2 Decide how many electrons will be in the last shell of element (Y) and to
which group it belongs, based on the following successive ionisation energies.
590, 1145, 4912, 6474, 8144 kj/mol.
Answers
Grp 2
Explanation:
the element has 2 valence electrons because there is a remarkable jump between IE2 and IE3 . When Y loses 2 electrons it gains a stable electronic configuration of a noble gas and then more energy need to be supplied to take out 1 more electron
So it belongs to group 2.
It could also be the case where the atom Y achieves a stable electronic configuration of half filled orbitals after losing 2 electrons . in this case it could have 5,7,or 9 valence elrctrons. So Y can belong to group 5,7, or 9.
case of 1 valence electron is neglected here because upon losing 1 e it will become noble gas and then the remarkable jump should be between IE1 and IE2.
*****Generally half filled orbital case is not considered in these type of questions at school level *******