Question

The $1^{\text {st }}, 2^{\text {nd }}$, and the $3^{\text {rd }}$ ionization enthalpies, $I_{1}, I_{2}$, and $I_{3}$, of four atoms with atomic numbers $n, n+1$, $n+2$, and $n+3$, where 𝑛 < 10, are tabulated below. What is the value of n?Atomic Number	Ionization Enthalpy (kJ/mol)
I 1	I 2
n	1681
n+1	2081
n+2	469
n+3	738

Answer 1

Since I.E. of Na is 495.8 kJ mol–1 , so (n + 2) should be 11.
n + 2 = 11, So n = 9