1. Introduction to Bonding
March 5, 2007

2. Practice Problems
Rank these atoms from lowest number of unpaired electrons to highest number of unpaired electrons in their ground state electron configurations?
F, Sb, Fe, Mn, S, Ar
Place the following elements and ions in order of increasing size (smallest to largest).
As-, Se, Cl, F, He+
Ar < F < S < Sb < Fe < Mn
He+ < F < Cl < Se < As-

3. Electron Config Exceptions
Transition metals exhibit many exceptions to the filling of atomic orbitals
Memorize the Cu and Cr exception
Assume the rest of the transition metals obey the rules
But what about when transition metals form ions? They lose electrons to form cations
They lose “s” valence electrons first.

4. Bonding Energy
Why do atoms form bonds?
Lower energy when bonds form

5. Chemical Bond Types Ionic compounds form ionic bonds
donation of electrons
Covalent compounds
sharing of electrons
How do we predict the compound types?
Electronegativity (EN) – tendency of atoms in bonds to attract bonding electrons to itself.

6. Electronegativity Values
EN values increase going to the upper right of the periodic table. (Noble gases not included)

7. Bond Types Same two nonmetals Two different nonmetals
A metal and a nonmetal

8. Bond Dipole Examples