Question

Observe the $I{P_1},I{P_2},I{P_3}$ and $I{P_4}$ , respectively for the elements $A,B,C,D$ . Identify which elements have $3{e^ - }$ in the outermost shell. (all values are in $kJ/mol$ ).
A. $786,1577,3231,4355$
B. $737,1450,7732,10540$
C. $495,4562,6912,9544$
D. $800,2427,3659,25025$

Answer 1

Hint:The amount of energy required to remove an electron from a neutrally isolated gaseous atom to convert it into a positive charged cation is known as the ionization enthalpy. The greater the effective nuclear charge of the nucleus on the outermost valence shell electron, the greater the value of ionization enthalpy.

Complete step by step answer:
The conversion of the neutrally isolated gaseous atom into a cation takes place through a single step where the ground state atom undergoes absorption of first ionization enthalpy.
$X\xrightarrow{{I{P_1}}}{X^ + } + {e^ - }$
Similarly, in order to extract another electron from the first excited state of the ground state atom, a second ionization enthalpy is provided.
${X^ + }\xrightarrow{{I{P_2}}}{X^{ + 2}} + 2{e^ - }$
In the same manner, in order to extract another electron from the second excited state of the ground state atom, a third ionization enthalpy is provided.
${X^{ + 2}}\xrightarrow{{I{P_3}}}{X^{ + 3}} + 3{e^ - }$
As per the question, we need to determine the element which has a total of three electrons in its valence shell. This means that as soon as we extract the third electron from the valence shell of the element, it attains the configuration of the nearest noble gas and is in a much stable state. This signifies that the value of the fourth ionization enthalpy should increase exponentially for the element. Out of the four combinations provided above, we can find this rapid exponential increase in ionization enthalpy only in one option.
Thus, the correct option is D. $800,2427,3659,25025$ .

Note: The value of ionization enthalpy increases across a period due to an increase in the effective nuclear charge and decrease in the size of the atom. Similarly, the value of ionization enthalpy decreases down the group due to addition of new shells and an increase in the size of the atoms.