A Note To The Granddaughters
Our older granddaughter, eleven years old, and who lives just across the street from us, developed a fever several days ago which has not abated; it has been as high as 104, and even yesterday -- about four days into this non-Ebola event -- she had a fever of 103.1. Except for a minor, relatively non-productive cough, she did not exhibit any other symptoms. Of course, the first question I asked last Friday was whether she had recently returned from West Africa.
The worse part about the illness at the moment is that she won't be able to go swimming. She participates in competitive swimming and in spashball. Splashball is essentially water soccer/polo with few rules except no intentional drowning of other players. Tonight would have been splashball.
The best part of her swimming evenings (Monday - Thursday) is my getting to drive her to the pool. It's the one time of each day we have 20 minutes (each way) completely free to talk about any subject of common interest.
The other day were talking about chemical bonds: ionic bonds and covalent bonds. I was unable to explain the nuances of ionic bonding vs covalent bonding: it's been a long time since I last studied organic and inorganic chemistry.
So, now back to the books. I am relieved. I now understand why I had difficulty with the nuances of bonding. From William H Brown's Introduction to Organic and Biochemistry, c. 1987.
One way of estimating the degree of ionic or covalent character in a chemical bond is to compare the electronegativities of the atoms involved.That is so cool. It continues:
Electronegativity measures the force of attraction an atom has for the electrons it shares in a chemical bond with another atom. The most widely used scale of electronegativities was devised by Linus Pauling int he 1930s; it is based on bond energies of diatomic molecules. On this scale, fluorine, the most electronegative element, is assigned an electronegativity of 4.0 and all other elements are assigned values relative to fluorine.And here's one way of determining whether a bond is ionic or covalent: "as an approximation, an ionic bond is formed with the difference in electronegativity between two elements is 1.7 or greater."
I must have missed that day in high school/college when this was explained. The source, as noted, is c. 1987, so a lot of things may have changed since then, but ... whatever.
Another reason I find this so cool is that it was Linus Pauling that came up with this. I am most familiar with "the" Linus Pauling as "described" by James Watson in The Double Helix, 1968. Wow, the first half of the 20th century was quite incredible.
Since then, as one character in "The Big Bang Theory" has said: "not much has happened."