1. Periodic Table & Bonding

2. ALL elements have a neutral (zero) charge off the periodic table.
Example: Sodium (element 11)
Na 11 protons (11+) {atomic number}
11 electrons (11-)
0 charge overall
** Just as a reminder: Neutrons can be calculated as well,if needed. (Atomic mass – atomic number)
= 12 neutrons

3. ELEMENTS are pure substances.
Examples: Calcium (Ca), Sodium (Na), Chlorine (Cl), Oxygen (O), Nitrogen (N)
COMPOUNDS are combinations of elements.
To do that, elements become ions that contain charges, then they are attracted due to opposite charges.

4. Ca+2 Cl-1 [Charges must equal zero!] Cl-1
For example:
Na Cl [Charges must equal zero!]
NaCl (table salt is produced) OR
Ca Cl-1 [Charges must equal zero!]
Cl-1
CaCl The small number indicates how MANY were needed

5. Q: So, how do I know the charges (oxidation numbers) of the ions?
A: By looking at their location on the periodic table, their oxidations are evident.
Let’s see how that works

6. Here are the oxidations for the main columns of the periodic table:

7. Here are a few more examples:
Ca O-2 so…….. CaO
Na O-2 so …… Na2O
Ca N-3 so ……. Ca3N2
(hint: mathematically they both go into 6)
Now you try:
Li Cl produces ??????
Na N produces ??????
Mg Br produces ??????

8. Here are the answers:
LiCl (charges already equal zero)
Na3N (It takes 3 Na to equal the N)
MgBr2 (It takes 2 Br to equal the Mg)
** Remember:
All charges came from their location on the chart.