Atomic binding in metals: The attraction between the nucleus and the valence electron of a copper atom is best described as which of the following?

Introduction / Context:
In metallic solids such as copper, valence electrons are delocalized and participate in metallic bonding, forming an electron sea. The individual attraction between a given nucleus and a valence electron is therefore weaker than in covalent or ionic bonds where electrons are localized between specific atoms or ions.

Given Data / Assumptions:

• Copper has a single s-type valence electron beyond a filled d-shell.
• In the solid, this electron is delocalized across the lattice.
• We refer to effective binding of valence electrons in metals.

Concept / Approach:

Delocalization causes conduction electrons to respond readily to applied fields and thermal energy, evidenced by good electrical and thermal conductivity. A strong nucleus–valence electron attraction would impede conduction. Zero attraction is unphysical; electrostatic forces always exist, but in the collective metallic environment the effective binding is weak compared to localized bonding scenarios.

Step-by-Step Solution:

Verification / Alternative check:

Band theory shows partially filled bands in copper; the small effective mass and high mobility align with weak localization of valence electrons.

Why Other Options Are Wrong:

• Zero: Contradicts Coulomb interaction; cannot be exactly zero.
• Strong: Inconsistent with metallic conduction behavior.
• Either zero or strong/variable-zero: Not a physically meaningful description.

Common Pitfalls:

• Equating core electron binding (strong) with valence electron binding (much weaker in metals).

Final Answer:

weak