"…the British chemist John Dalton (1766-1844) provided the basic theory: all matter–whether element, compound or mixture–is composed of small particles called atoms."
– Ebbing and Gammon. General Chemistry, 8th ed. (New York: Houghton Mifflin, 2008), 42.
If the quoted text above were on Wikipedia, rather than in a traditionally published textbook, it would be tagged citation needed. Instead it has no reference at all: nothing inline, no footnotes, no endnotes. Nothing. And from a brief survey of chemistry textbooks (the handful sitting on my shelves), this is common.
Articles on super-resolution microscopy often start by describing the diffraction limit. It would be unthinkable not to cite Ernst Abbe's work on the subject. If I were writing for a textbook, though, it appears I could say:
"Ernst Abbe (1840-1905) discovered that the resolution of a microscope is wavelength-dependent"
and leave it at that.
It seems so unscientific to me to provide such conclusions without their accompanying evidence. The exciting questions in science, I believe, come out of why, how and how do you know? and I think a textbook should answer those questions, even if it's just a reference to details elsewhere.
So that's what I'm going to do: find the missing references to the details of major discoveries covered in general chemistry textbooks like Ebbing & Gammon.
Others, particularly Dr. Carmen Giunta at Le Moyne College and the folks behind ChemTeam, have collected some of the classic works online. Dr. William Jensen, of the University of Cincinnati, had a delightful "Ask the historian" column in the Journal of Chemical Education, as well. My hope is that my list will be more searchable and (eventually) comprehensive.