The authors reply to Scerri

We appreciate the comments of Scerri on our recent articles. He is correct that our discussion on p 621 is incorrect. The data in Table 3 are correct, but our next-to-the-last sentence in the paragraph on scandium is convoluted and in error; however this has no impact on the main ideas discussed.

Scerri comments that we state that Allen's scale is the only one that involves directly measurable quantities. We do not state this anywhere in the article. We do state that none of the electronegativity scales in current use can give an exact value for the electronegativity of an atom in a molecule because electronegativity is by nature a qualitative concept.

In at least five separate places in the article we do state our rationale for using Allen's electronegativities. In the first paragraph we state that: "ionization energies provide a convenient methodthat is simpler and more appropriate for the introductory course." On p 628 we write: "In our view, students will better understand and appreciate this important concept if it can be developed in a manner consistent with simple models of atomic structure and properties." On p 629: "Their [electronegativities] origin is evident and clear to the students, and their development is consistent with that for previous topics in the course." Further on p 629: "AVEE electronegativity values have the advantage that students can see where they come from and can calculate the values themselves." Page 631: "The origin of the Allen electronegativities values can be easily introduced in general chemistry courses, whereas other electronegativity scales have a basis beyond the comprehension of most beginning students."

Scerri has very succinctly stated our rationale: "Allen's scale of electronegativitiesmaintains the connection with ionization energy that is used by the authors to develop shell structure". We believe that this is a compelling reason for choosing this scale. There are some 15 electronegativity scales in use, all of which, including the Allen scale, give the same qualitative interpretation. It makes little difference which is used unless there is some distinguishing feature that argues for a particular choice. We believe that the Allen scale does demystify the electronegativity concept, and that pedagogically it is consistent with the concepts already introduced in the course. We have taken no stand on the overall usefulness of the Allen scale except for the consistency it provides in our scheme of demystifying the general course.