Topic: Modern Model of the atom - ORBTIALS

Principal Energy Levels (PEL)

• Also known as “shells”

• Can have values of 1, 2, 3, 4…..• (whole numbers)• Electrons in PEL’s with greater numbers

have greater energy.

• [Similar to rows of seats in a stadium)

Sublevels• Each principle energy level is

made up of 1 or more sublevels

1st PEL = s (1 sublevel) 2nd PEL = s,p (2 sublevels)3rd PEL = s,p,d (3 sublevels)4th PEL = s,p,d,f (4 sublevels)

Orbitals

• s has 1 orbital• p has 3 orbitals • d has 5 orbitals• f has 7 orbitals

• Each sublevel contains 1 or more orbitals• Each orbital holds a max of 2 electrons

1st PEL = s (1 sublevel) = 1 orbital (____ electrons)2nd PEL = s,p (2 sublevels) = 4 orbtials (____ electrons)3rd PEL = s,p,d (3 sublevels) = 9 orbitals (___ electrons)4th PEL = s,p,d,f (4 sublevels) = 16 orbitals (____ e-)

2

8

18

32

Memorize• S P D F• 1 3 5 7• 2e- 6e- 10e- 14e-

s

p

d

f

*Each orbital holds a max of 2 electrons

sublevels

# of orbitals

Max # of electrons

Orbitals• s orbital: sphere

• p orbital: dumbell

• d orbital: 4 clovers,1 double ended pacifier

• f orbital: funky!! Flowers? You describe!

• http://www.d.umn.edu/~pkiprof/ChemWebV2/AOs/ao4.html

Bohr Model vs. Modern Model

• Electron = particle• Orbit• Holds 2n2

electrons• Circular • Each orbit has

specific energy• Exact location

• Electron = Wave• Orbital• Holds 2 electrons• Not necessarily circular• Each orbital has

specific energy• Probable location

(wave mechanical model)

Electron configurations• Adding electrons to atoms

so that the electrons are in the lowest energy levels – most stable or ground state configuration

• Start with 1s, then work upward in order of increasing energy.

• Use Aufbau rule.

Aufbau

1s2

2s2 2p6

3s2 3p6 3d10

4s2 4p6 4d10 4f14

5s2 5p6 5d10 5f14

6s2 6p6 6d10

7s2 7p6 7d10

1s2

2s2 2p6

3s2 3p6 3d10

4s2 4p6 4d10 4f14

5s2 5p6 5d10 5f14

6s2 6p6 6d10

7s2 7p6 7d10

He

C

Mg

Zn

1s2

1s22s22p2

1s22s22p63s2

1s22s22p63s23p6 4s23d10

He

C

Mg

Zn

1s2

1s22s22p2

1s22s22p63s2

1s22s22p63s23p6 4s23d10

From these modern configurations, we can figure out Bohr Configurations

All you have to do is add up the electrons in each shell (PEL)

1 = 2

2

1 = 2 2 = 2+2

2 – 4

1 = 2 2 = 2+6 3 = 2

2 – 8 – 2

1 = 2 2 = 2+6 3 = 2+6+10 4=2

2 – 8 – 18 – 2

Orbital Diagrams

Shows the orbital the electron is located in

Shows the spin – they have to be opposite!(spin up or spin down)

Hund’s Rule• Maximum multiplicity – most e- with

same spin.– So, Fill up before pairing up

• 1s2 2s2 2p4

Which element?How many unpaired e-? How many PEL’s occupy?How many PEL’s are fully occupied?How many sublevels contain e-?How many sublevels full?How many orbitals contain e-?

Boron

1

2

1

3

3

2