A portion of the first–ionization-energy data for Period 3 is provided.
Element
Mg
Al
Si
P
S
Cl
I1 (kJ mol−1)
738
578
787
1012
1000
1251
a. Calculate the percentage change in I1 when moving (i) from Mg to Al and (ii) from P to S. Show your work.
b. Based solely on your calculations and the numerical data, decide which of the two percentage changes represents a deviation from the overall trend across the period. Justify your decision quantitatively.