A Level Chemistry OCR Practice Exam

In the context of metallic bonding, what is electronic delocalization?

1. The sharing of electrons between two specific atoms

2. The free movement of electrons around metal ions

3. The confinement of electrons to tight orbits around protons

4. The absence of any electron movement in metals

The correct answer is: The free movement of electrons around metal ions

In metallic bonding, electronic delocalization refers to the phenomenon where electrons are not associated with any specific atom but are shared among many atoms within the metallic structure. This delocalization results in a "sea of electrons" that move freely around positively charged metal ions. This free movement contributes to various properties of metals, such as electrical conductivity and malleability. The other options describe scenarios that do not accurately depict metallic bonding. For instance, the sharing of electrons between two specific atoms would characterize covalent bonding rather than the delocalized nature of electrons in metals. Confining electrons to tight orbits around protons aligns more closely with the behavior observed in atomic models of non-metallic elements, where electrons are primarily localized. Finally, stating that there is an absence of electron movement in metals contradicts the fundamental understanding of metallic bonding, which is defined by the mobility of delocalized electrons.