Select the correct answer.

Which pair of elements can form ionic bonds?

A.

copper (Cu) and nitrogen (N)

B.

gallium (Ga) and phosphorus (P)

C.

hydrogen (H) and sulfur (S)

D.

phosphorus (P) and fluorine (F)

E.

potassium (K) and bromine (Br)

E-potassium and bromine for plato and edmentum users

Ionic bond is a chemical bond formed by the complete transfer of electrons between two atoms. The atom that loses electrons gains a positive charge (cation) and that which accepts electrons gains a negative charge (anion). Now, electronegativity is a parameter that measures the tendency of an atom to accept electrons. In the context of ionic bonding, two elements which show a significant difference in their electronegativity values form ionic bonds.

In the given examples, the difference in electronegativity is greatest between K and Br i. e. 0.8 and 2.8 respectively with a difference of 2.0. This also makes sense since K and Br are on the extreme ends of the periodic table. Hence, potassium with a valence electron configuration of 4s1 will lose its s electron to Br (4s24p6) and form an ionic molecule K⁺Br⁻

Ans E) potassium and bromine