Evolution of the Atomic Model: 1924-1926

Williamsburg High School for Architecture and Design

Mr. Quinn and Ms. Tom10/9/13

AimHow can we “fix” the Octet Rule?

(TOPIC: How did the concept of the atom change in the early 1900s?)

Remember the Bohr model!

The Bohr Model● The electrons were

confined into clearly

defined orbits.

● They could jump between

these orbits, but could not

freely spiral inward or

outward in intermediate

states.

● An electron must absorb

or emit specific amounts

of energy for transition

between these fixed orbits.

OK, but why are they stuck in orbits?

All matter is made of waves!

Well, you see...

Let’s take it back a step...

Artist’s Rendition

Those waves are all over the place!

That’s why orbits are the most likely location of electrons in the atom!

How do all those waves loop around each other???

Think back...

● How many electrons can the first shell hold?○ What does that correspond to on the periodic

table?

● How many electrons can the second shell hold?○ What does that correspond to on the periodic

table?

● Which elements was the octet rule funky for?○ What does that correspond to on the periodic

table?

Each orbit is actually a bunch of subdivisions!

Row # Sublevels

ID Sublevels

1

2

3

4

Sublevel # Orbitals Electrons/ orbital

Total Electrons

s

p

d

f

How do we fill them?

1s

2s 2p

3s 3p 3d

4s 4p 4d 4f

5s 5p 5d 5f

How do we write that?

● He

● Be

● F

● Mg

● Cl

● Ca

● Br

● Ag

Does that fix our problem?

● How many electrons did we expect to have in the outer shell of Br?

● How many did we get?

MORE PRACTICE!