Gen Chem Ch9 Lec 1

(5/4/20, bes)

Sorry i am so late...got caught up in grading.

Chapter 9: Chemical Bonding

As we are all aware, elements in the periodic table form associations with other elements...the question is why? I am going to answer this for your in the following discussion.

The most stable elements in the periodic table are the nobel gases, He, Ne, Ar, Kr, Xe, Rn. Why? The answer is that they have a full shell of electrons.

- He --> full 1s (this one is a bit different and is why it sometimes shows up in the periodic table over near H)

- Ne --> full 2s and 2p

- Ar --> full 3s and 3p

- Kr --> full 4s and 4p

- Xe --> full 5s and 5p

- Rn --> full 6s and 6p

Ionic Bonding (Sec 9.2)

So one of the most common ionic compound we discussed was NaCl...why is this so stable...

- Na 1s2 2s2 2p6 3s1... if it loses 1 electron then it has the electron configuration of Ne.

- Cl 1s2 2s2 2p6 3s2 3p5... if it gains 1 electron then it has the electron configuration of Ar.

So, NaCl is sort of like NeAr, but since Na+ is a cation and Cl- is an anion, they strongly associate with each other forming a strong ionic bond.

The above discussion holds for all of the alkali metals and halogens.

The same goes for all of the alkaline earth metals...except these lose 2 electrons from the "s-orbital" and hence associate with 2 halogen anions, ex. CaCl₂.

Please look over this book section...end of this short lecture :)