10/28/09

The electrons in te both the cations and anions are in higher energy levels as one reads down a group.

There is a gradual increase of ionic radii down a group

Valence Elctrons

Chemical compunds for because electrons are lost, gained, orshared between atoms

The electrons that interacts in this manner are those in the highest energy level

The electrons available to be lost, gained, or shared in the formation of chemical compundsare referred to as valence elctrons

Valence electrons are often located in the incompletely filled main-enrgy levels

Example: The electron lost from the 3s sublevel of Na to form Na+ is a valence electon

Electronegativity

Valence electrons hold atoms togehter in chemical compounds

In many cmpounds, the negative charge of the valence eectron is concentrted closer to one atom than to another

Electronegativit is a measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound

Electronegatvities tend to increase across periods and decrease or remain about the same down a group

Need to Know on the Periodic Table

Groups 1 and 2

Inner T.M

Main Group(s&p)

Halogens(17)

Noble gases(18)

Metals(+ ions)

Nonmetals(-ions)

Metaloids

Atomic radius increase from bottom up and right to left

Ionization energy incrreases from bottom to top and left to right

Electron affinity increases bottom to top and left to right

Electronegativity increases bottom to top and left to right

ions!

(+) Cations smaller than original atom

(-) Anions larger than originl atoms