Which of the following pairs of elements is most likely to form an ionic bond?

A.

carbon and chlorine

B.

phosphorous and bromine

C.

sulfur and oxygen

D.

sodium and sulfur

Answer is: D. sodium and sulfur.

When the electronegativity difference is greater, the bond polarity is increasing ...

Electronegativity (χ) is a property that describes the tendency of an atom to attract a shared pair of electrons.

Atoms with higher electronegativity attracts more electrons towards it, electrons are closer to that atom.

Δχ (Na-S) = 2.6 - 0.95 = 1.655; electronegativity difference between sodium and sulfur.

Ionic bond is the electrostatic attraction between oppositely charged ions (cations and anions).

Sodium is metal (forms cation) and sulfur is nonmetal (forms anion).