Final answer:
Graphite is ideal for electric motor contacts due to its structural properties where carbon atoms are connected via sp² hybridization, forming a planar arrangement. The overlap of p orbitals between carbon atoms allows for delocalized electrons and excellent electrical conductivity, while weak interlayer London forces give it slipperiness.
Step-by-step explanation:
Graphite's properties make it ideal for use in electric motor contacts due to its structure and bonding. Each carbon atom within a graphite layer is bound to three other carbons in a trigonal planar geometry, via sp² hybridization, contributing to its high melting point and sublimation at about 3915°C. This structure forms both σ (sigma) bonds and π (pi) bonds, with the latter allowing for delocalized electrons, which enable graphite's electrical conductivity.
Graphite consists of layers of six-membered rings of carbon atoms. The carbon layers are held together by weak London dispersion forces, giving graphite its soft and slippery characteristics useful in lubricants. These layers can slide over each other due to the weak interlayer forces, enhancing its suitability as a dry lubricant.
The resonance forms from the overlapping p orbitals across carbon atoms contribute to the system's stability and electrical conductivity. Impurities in graphite can increase its slipperiness by disrupting the regular stacking of the graphite layers and making the layers easier to slide past one another.