National Center for Biotechnology Information All about covalent compounds! What are the properties of covalent compounds? Covalent compounds have the following properties (keep in mind that these are only general properties, and that there are always exceptions to every rule): 1) Covalent compounds generally have much lower melting and boiling points than ionic compounds. As you may recall, ionic compounds have very high melting and boiling points because it takes a lot of energy for all of the + and - charges which make up the crystal to get pulled apart from each other. Essentially, when we have an ionic compound, we need to break all of the ionic bonds in order to make it melt. On the other hand, when we have covalent compounds we don't need to break any bonds at all. 2) Covalent compounds are soft and squishy (compared to ionic compounds, anyway). The reason for this is similar to the reason that covalent compounds have low melting and boiling points. Think of it like this: Ionic compounds are like giant Lego sculptures.
Pictures of Science: 700 Years of Scientific and Medical Illustration - NYPL Digital Collections Collection History This digital collection draws upon the materials selected for an exhibition called "Seeing Is Believing," held in the Library's Gottesman Exhibition Hall, October 23, 1999 - February 19, 2000. Natural history materials were included very selectively in that exhibition; however, natural history materials have their own separate presentations in NYPL Digital Gallery, devoted to plants and to animals respectively. Background The digital presentation reprises the exhibition's overarching premise: pictures, as Leonhart Fuchs noted in the introduction to his great herbal of 1542, "can communicate information much more clearly than the words of even the most eloquent men." The exhibition posited three categories of scientific images. The exhibition and this digital presentation share the same proviso. Related Resources Baigrie, Brian S., ed. Ford, Brian J. Horblitt, Harrison. Lee, Jennifer B. and Miriam Mandelbaum. NYPL. _____. Robin, Harry. Tufte, Edward R.
PLOS | Public Library Of Science The Feynman Lectures on Physics Science News, Articles, and Information - Scientific American OnLineLabs ChemLab There is a fee for this one, but it is well worth the price! They are truly interactive and you can design your own simulations! Go to the downloads page for a free evaluation trial Dartmouth ChemLab This site has some very good interactive virtual labs plus a terrific interactive periodic table! Virtual Chemistry Chemistry and Physics applets and phylsets from Davidson University. You can also download and use on your own webpages. Virtual Chemistry Lab This site has virtual experiments as well as webcasts on chemistry topics.
Molecular Workbench - An Interface to the Molecular World
The history of modern science reflected in the life of its seminal practitioner. by nda_librarian Apr 30