Question

Atomic number of element with lowest first ionisation enthalpy is

• A. 32
• B. 19
• C. 35
• D. 87

Hint:

To find the element with the lowest ionization energy, focus on the alkali metals, especially those with the lowest atomic numbers (e.g., Francium).

Answer 1

The Correct Option is D

The first ionization enthalpy is the energy needed to detach one mole of electrons from one mole of gaseous atoms. - Elements in Group 1 of the periodic table generally exhibit low ionization enthalpies. Their outermost shell contains a single electron, which is readily removed. - Considering the provided options: - Element 32 (Germanium) is a Group 14 element with a relatively high ionization enthalpy. - Element 19 (Potassium) belongs to Group 1 but does not possess the lowest ionization enthalpy. - Element 35 (Bromine) is a halogen, and halogens are characterized by high ionization energies. - Element 87 (Francium) is a Group 1 alkali metal and demonstrates the lowest first ionization enthalpy. This is attributed to alkali metals' single valence electron, resulting in very low ionization energies. Therefore, the correct selection is (4) 87, which represents Francium.