The complex compound formed by the combination of two elements with a large electronegativity difference is likely to be

Analyze the question

The question asks what type of bonding is likely when two elements have a large electronegativity difference. The wording "complex compound" is a bit odd, but the key idea is the electronegativity difference.

Concept

Electronegativity is an atom's ability to attract the shared electrons in a bond. The difference between the two atoms decides the bond type:

| Electronegativity difference | Bond type | |---|---| | 0 (or very small) | Non-polar covalent | | Moderate (about 0.4 – 1.7) | Polar covalent | | Large (above about 1.7) | Ionic |

Solution

1. When the difference is large, one atom (the more electronegative) pulls the bonding electrons so strongly that they are effectively transferred completely.
2. This forms positive ions (cations) and negative ions (anions).
3. These oppositely charged ions are held together by strong electrostatic attraction, which is an ionic bond.

Example: In NaCl, Na has an electronegativity of 0.9 and Cl has 3.0. The difference is 2.1, which is large, so NaCl is ionic.

Checking the other options

• A. Polar covalent: Happens with a moderate difference (e.g. HCl, H₂O), not a large one.
• B. Giant molecular: This describes a structure (like diamond or silica) and is not determined by a large electronegativity difference.
• C. Covalent: Involves sharing of electrons, which is expected when the difference is small or moderate.
• D. Ionic: Matches a large electronegativity difference. ✔

Exam tip

Remember: "Big gap = give and take (ionic); small gap = share (covalent)." Metal + non-metal usually means a large difference, so expect ionic bonding.