International General Certificate of Secondary Education (IGCSE) Chemistry Practice Exam

What is defined as a strong attraction between a shared pair of electrons and two nuclei?

1. Covalent bond

2. Ionic bond

3. Metallic bond

4. Hydrogen bond

The correct answer is: Covalent bond

A covalent bond is defined as a strong attraction between a shared pair of electrons and two nuclei. This type of bond occurs when two atoms come together and share electrons to achieve a more stable electron configuration, often filling their outer electron shells. The shared electrons are attracted to both nuclei, which provides a strong force that holds the atoms together. In contrast, ionic bonds involve the transfer of electrons from one atom to another, resulting in a strong electrostatic attraction between positively and negatively charged ions. Metallic bonds, on the other hand, arise from the attraction between metal ions and free-moving electrons, forming a "sea of electrons" that contributes to the conductivity and malleability of metals. Hydrogen bonds are relatively weak interactions that occur between a hydrogen atom bonded to a highly electronegative atom and another electronegative atom. These bonds play a significant role in the properties of water and the structure of biological molecules, but they do not involve shared electrons like covalent bonds do.