The problem of the peculiarcharacter of chemical laws and theories is a central topic in philosophy of chemistry. Oneof the most characteristic and, at the sametime, most puzzling examples in discussions onchemical laws and theories is Mendeleev''speriodic law. This law seems to be essentiallydifferent in its nature from the exact laws ofclassical physics, the latter being usuallyregarded as a paradigm of science byphilosophers. In this paper the main argumentsconcerning the peculiar character of chemicallaws and theories are examined. The laws ofchemistry (...) are natural laws to the same extentas are the laws of physics. The law discoveredby Mendeleev is a normal law of nature. It isnot a law of physics, nevertheless, it is exactin the same philosophical sense as are the lawsof physics. The periodic system of chemicalelements was established by constructing anidealized system of idealized elements. Thefundamental idealization substantiated byexperimental chemistry was the chemicalelement as a place in the periodicsystem. (shrink)