1. The Octet Rule
When atoms form ions or combine in compounds, they try to get the electron configuration of the nearest Inert Gas
IN OTHER WORDS…
they try to get 8
electrons in
their outermost shell

2. Warm-up Exercise!

3. Where do we look on the Table to get into the Third energy level?
If the first energy level can have 2 e- and the second and subsequent energy levels can each have 8 e- , then what is the first atom to have an e- in the third energy level?
Sodium

4. Why do we need to know this?
It’s important to be able to quickly locate the atoms with a certain number of electrons in the outer shell, or highest energy orbital, because it helps you predict how it will interact with other atoms.
This outer shell determines the Valence of the atom.

5. Electrovalence (but we can just call it “Valence”)
Definition: Valence - the measure of how much an atom wants to bond with other atoms.
Too easy, huh?

6. In fact, once we understand the structure...
…The valence electrons are the ONLY ones we have to worry about to determine an atoms bonding characteristic!
This outer shell determines the Valence of the atom.

7. The Octet Rule
When atoms form ions or combine in compounds, they try to get the electron configuration of the nearest Inert Gas
IN OTHER WORDS…
they try to get 8
electrons in
their outermost shell

8. Valence Electrons
The electrons in the outermost shell – or energy level – of an atom
Periodic – which means they occur in a repeating pattern.
Elements in Group IA have 1 valence electron
Elements in Group IIA have 2 valence electrons
Can you guess how many valence electrons Si (Silicon) has?
Group IVA, so 4
How about S (Sulfur)?
Group VIA, so 6
Br (Bromine)?
Group VIIA, so 7

9. Different types of Bonding
There are 2 bond types : ionic and covalent
In ionic bonding one atom has a stronger attraction for electrons than the other, and “steals” an electron from a second atom
In covalent bonding the attraction for electrons is similar for two atoms. They share their electrons to obtain an octet.

10. IONIC BONDING Occurs between a metal and a nonmetal.
The NON-metal “steals” the electron from the metal. WHY? (Think about our discussion of what makes a “happy” atom…

11. Ionic bonding Ionic bonding involves 3 steps (3 energies)
1) loss of an electron(s) by one element, 2) gain of electron(s) by a second element, 3) attraction between positive and negative e– 1) 2) Na Cl 3)
Cl–
Na+
Cl–
Na+

12. Valence electron Na
Chlorine

13. The NaCl Ionic Lattice