Question

The first ionisation energies of magnesium and aluminium are respectively given by

• A. 7.64, 5.98
• B. 7.64, 7.64
• C. 5.98, 7.64
• D. 5.98, 5.98

Answer 1

Answer: (A)

$IE$ of $Mg>IE$ of $Al$

Electronic configuration of

$\text{Mg}=1{\text{s}}^2,2{\text{s}}^2,2{\text{p}}^2,3{\text{s}}^2$

$\text{Al}=1{\text{s}}^2,2{\text{s}}^2,2{\text{p}}^6,3{\text{s}}^2,3{\text{p}}^1$

$Mg$ has stable configuration (fulfilled) than $Al$ so removal of an electron is difficult hence, required more energy i.e. more ionisation energy.