Question

On the basis of electronegativity, which of these pairs of elements is most likely to form monatomic ions?

Cl and Na

K and Rb

Ba and Ca

Na and K

Answer 1

"Cl and Na" is the one pair among the following choices given in the question that is most likely to form monatomic ions on the basis of electronegativity. The correct option among all the options that are given in the question is the first option. I hope the answer has come to your great help.

Answer 2

Answer is: Cl and Na.

sodium and chlorine are in third period and they have very different properties. Sodium is solid metal and chlorine is gaseous nonmetal.

They form compound NaCl (Sodium chloride), because sodium lost one valence electron and form cation Na⁺, chlorine gain one electron and form anion Cl⁻.

Electron configuration of sodium atom: ₁₁Na 1s² 2s² 2p⁶ 3s¹.

Electron configuration of chlorine atom: ₁₇Cl 1s² 2s² 2p⁶ 3s² 3p⁵.

Other examples are metal-metal pairs and they do not form cation and anion.