HARD-VS-SOFT-1 - 1 1.1 Hard vs soft When are ionic bonds...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Hard vs. soft 1.1 When are ionic bonds strong? Ionic bonds are strong when the electrons have really transferred from the cation to the anion. In NaF Δ χ is 3.1 and therefore an electron really can be thought to have transferred from the electropositive sodium atom to the electronegative ±uorine atom. So ionic bonds are strong when Δ χ is a large number. Furthermore, we know that the electric potential energy, V q c q a r , where q c , q a and r are respectively the cation charge, the anion charge, and the distance between the cation and anion. Thus cations with a 2+ charge are twice as strong as 1+ charges, while 4+ charges have a whopping four times greater potential energy. Large charges on either the cation or the anion lead to strong ionic bonds. At the same time small r leads to stronger ionic bonds; small cations and anions, as they have smaller r associated to them, have stronger ionic bonds. In the table below, we list some common cations and anions and list the observed strength of
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/01/2011 for the course CHEM 2090 taught by Professor Zax,d during the Winter '07 term at Cornell.

Ask a homework question - tutors are online