This document discusses surface chemistry and adsorption. It defines surface chemistry as the study of phenomena occurring on substance surfaces and adsorption as the accumulation of molecules at an interface. There are two types of adsorption: physisorption, which involves weak van der Waals forces, and chemisorption, which involves stronger chemical bonding. Chemisorption is surface specific and can involve surface reactions like dissociation. The extent of adsorption increases with greater surface area as more sites are available for molecules to bond to.