Ions

__The Octet Rule__
The noble gasses do not react with other elements. In other words, noble gasses are very stable. Let’s look at the electron configuration of noble gasses (note: K is the name given to shell 1, L to 2, etc.)


 * = Element ||= Shell K ||= Shell L ||= Shell M ||= Shell N ||= Shell O ||= Shell P ||
 * = He ||= 2 ||=  ||=   ||=   ||=   ||=   ||
 * = Ne ||= 2 ||= 8 ||=  ||=   ||=   ||=   ||
 * = Ar ||= 2 ||= 8 ||= 8 ||=  ||=   ||=   ||
 * = Kr ||= 2 ||= 8 ||= 18 ||= 8 ||=  ||=   ||
 * = Xe ||= 2 ||= 8 ||= 18 ||= 18 ||= 8 ||=  ||
 * = Rn ||= 2 ||= 8 ||= 18 ||= 18 ||= 18 ||= 8 ||

As stated, when atoms form ions they seek an electron configuration like that of the nearest noble gas. Nearest refers to the number of representative elements between an element and a noble gas. For example Br is 1 space removed from Kr, but 7 spaces removed from Ar (see your periodic table). So, Br would gain 1 electron to form Br–.

Now practice the formation of anions and cations by completing the assignment below. The hand copy of the assignment must be submitted at the beginning of the next class.

Give the symbol, distance removed from the noble series, the amount of electron lost or gained to form a stable ion, and the ionic charge of a molecule of that element. An example is shown below.

Bromine: Br, 1 space from the noble series, gains 1 electron, Br- 1. Sodium 2. Oxygen 3. Calcium 4. Aluminum 5. Chlorine