Electron Location: Part III

Electron Configuration

Principle Quantum # (n)LEVEL/SIZE 1 2 3 4

Angular Quantum # (l)

ORBITAL SHAPE or

SUBLEVEL

s s p s p d s p d f

Magnetic Quantum #

(m)AXIS/

ORIENTATION

or ORBITALS

1

only 1 orbital

1 3

4 totalorbitals

1 3 5

9 total orbitals

1 3 5 7

16 total orbitals

Spin Quantum # (s)

DIRECTION OF

ELECTRON SPIN

2 e- 8 e- 18 e- 32 e-

Table 3-6b Orbitals and Electron Capacity of the First Four Principle Energy Levels

Principle energy level (n)

Type of sublevel

Number of orbitals per type

Number of orbitals

per level(n2)

Maximum number of electrons

(2n2)

1 s 1 1 2

2s 1

4 8p 3

3

s 1

9 18p 3

d 5

4

s 1

16 32p 3

d 5

f 7

1s

2p

2s

3d

3p

3s

4f

4d

4p

4s

2 (1)

2 (1)

2 (1)

6 (3)

6 (3)

2 (1)

6 (3)

10 (5)

14 (7)

10 (5)

2

32

18

8

= sub-level= max. # of electrons= # of electrons= number of orbitals

Principal Energy LevelsPrincipal Energy LevelsPrincipal energy level

Number of sublevels

Type of sublevel and (# of orbitals)

n = 1 1 1s

n = 2 2 2s (1) 2p (3)

n = 3 3 3s (1) 3p (3) 3d (5)

n = 4 4 4s (1) 4p(3) 4d(5)

4f (7)

“Rules” for Writing Electron Configurations a method of writing where electrons are

found in various orbitals around the nulcei of atoms. three rules in order to determine this:

1. aufbau principle

2. Pauli exclusion principle

3. Hund’s rule

Aufbau Principle electrons occupy the orbitals of the

lowest energy first each written represents an atomic

orbital (such as or or or ….) electrons in the same sublevel have equal

energy ( ) principle energy levels (1,2,3,4..) can

overlap one anotherex: 4s orbital has less energy than a 3d orbital

“know” these two exceptions to the Aufbau principle!  (There are many others at the bottom of the table that we won't memorize)

Cr we would predict: 1s2 2s2 2p6 3s2 3p6 4s2 3d4

but it is actually:1s2 2s2 2p6 3s2 3p6 4s13d5

Cu we would predict: 1s2 2s2 2p6 3s2 3p6 4s2 3d9

but it is actually:1s2 2s2 2p6 3s2 3p6  4s1 3d10

Pauli Exclusion Priciple

only two electrons in an orbitalmust have opposite spins represents one electron represents two electrons in an orbital

Hund’s Rules every orbital in a subshell must have one

electron before any one orbital has two electrons

all electrons in singly occupied orbitals have the same spin.

Order of ElectronsOrder of Electrons

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p

Writing Electron Configurations To write out the electron configuration of an

atom:use the principal quantum number/energy

level (1,2,3, or 4…) use the letter term for each sub-level (s,p,d, or f); use a superscript number indicates how many

electrons are present in each sub-level hydrogen =1s1. Lithium =1s22s1.

don’t write anything for spin (yet)

Orbital Energy DiagramsOrbital Energy Diagrams

http://colossus.chem.umass.edu/genchem/whelan/class_images/Orbital_Energies.jpg

Carbon Carbon

Atomic # - 6 Atomic # - 6

Orbital Energy DiagramsOrbital Energy Diagrams

http://colossus.chem.umass.edu/genchem/whelan/class_images/Orbital_Energies.jpg

NeonNeon

Atomic # - 10 Atomic # - 10

Orbital Energy DiagramsOrbital Energy Diagrams

http://colossus.chem.umass.edu/genchem/whelan/class_images/Orbital_Energies.jpg

ScandiumScandium

Atomic # - 21Atomic # - 21