A laboratory technician compares wires made from pure copper and pure aluminum. Both wires have identical length and cross-sectional area. Each metal is characterized by the following data.
Numerical/Tabular Representation (all values at 298 K)
• Valence electrons per atom: Cu = 1, Al = 3
• Measured electrical resistivity: Cu = 1.7×10−8Ω⋅m, Al = 2.8×10−8Ω⋅m
• First-ionization energy: Cu = 745kJ⋅mol−1, Al = 578kJ⋅mol−1
Use the information above to analyze how metallic bonding accounts for the observed properties of the two metals.
(a) Describe, in terms of metallic bonding, why both copper and aluminum conduct electricity at room temperature.
(b) Despite aluminum providing three delocalized electrons per atom, copper has the lower resistivity. Explain this observation using atomic-level arguments involving metallic bonding and electronic structure.
(c) Both metals are noted for high ductility. Explain how the nature of metallic bonding allows layers of atoms in each metal to slide without fracture, and discuss how atomic size differences between Cu and Al influence their relative ease of deformation.