#### Transcript Electron Configurations

### Electron Configurations Of Atoms & Ions

### Men & their Rules

• Aufbau Principle: Start at the beginning (Electrons enter lowest energy level 1 st ) • Pauli Exclusion Principle: Only 2 allowed (Only 2 electrons allowed in any orbital) • Hund’s Rule: Stay solo as long as possible (For orbitals of equal energy, 1 electron enters each until all orbitals contain one before any pairs up.)

### Consequences of Aufbau Principle

• Electrons enter orbitals in order of increasing energy levels.

• This order is shown in text on page 111.

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

*But there are two exceptions, namely Cu & Cr, who subtract 1 from 4s and add it to 3d.*

### Consequences of Pauli exclusion

• The

*s*

orbital is filled with 2 electrons.

• The 3 different orientations of the

*p*

orbital,

*p x*

,

*p*

y , &

*p z*

, each contain a max of 2 electrons • The 5 different orientations of

*d*

orbitals,

*d*

xy

*d*

xz ,

*d*

y z ,

*d x 2 y 2*

, &

*d*

z 2 , can have max of 2 each.

• The 7 different orientations of

*f*

orbitals also only have 2 electrons for each suborbital.

### Consequences of Hund’s Rule

• One electron is added to

*p*

x , then 1 to

*p*

y , then 1 to

*p*

z , before the second one is added to

*p*

x . The 5 th electron is then added to

*p*

y , & 6 th to

*p*

z .

• The same pattern is observed for the

*d*

&

*f*

suborbitals.

• NOTE: The single electrons all have parallel spins. When the 2 nd electron is added to each suborbital, it spins in the opposite direction.

### Relating this to the periodic table:

• The “

*s*

block” = Groups IA & IIA • The “

*p*

block” = Groups IIIB – VIII (13-18) • The “

*d *

block” = Transition elements (Groups IIIA-IIB; Groups 3-12) • The “

*f*

block” = Rare earth metals

### What this means…

• You merely need to follow the periodic table to figure out electron configurations.

• The block (

*s, p, d, *

&

*f*

) indicates where the last electrons go.

• Follow the period numbers, 1-7, because these are your energy levels & then remember suborbitals penetrate differently.

–

*d*

block starts at 3

*d*

;

*f*

block starts at 4

*f*

### How can we apply this?

• Follow the periodic table numerically – 1

*s*

2 (takes you to He) 2

*s*

2 (to Mg) 3

*p*

6 (to Ar) 4

*s*

2 (to Be) 2 (to Ca) 3

*d p*

1-3 6 (to Ne) 3 (to V) ***

*s*

2 – Cr (1 st exception): 1

*s*

2 2

*s*

2 2

*p*

6 3

*s*

2 3

*p*

6 4

*s*

1 3

*d*

5 – Cu (2 nd exception): 1

*s*

2 2

*s*

2 2

*p*

6 3

*s*

2 3

*p*

6 4

*s*

1 3

*d*

10 • Mn: 1

*s*

2 2

*s*

2 2

*p*

6 3

*s*

2 3

*p*

6 4

*s*

2 3

*d*

5 • Zn: 1

*s*

2 2

*s*

2 2

*p*

6 3

*s*

2 3

*p*

6 4

*s*

2 3

*d*

10 – Ga: 1

*s*

2 2

*s*

2 2

*p*

6 3

*s*

2 3

*p*

6 4

*s*

2 3

*d*

10 4

*p*

x 1

### Applications,

*continued*

• La is beginning of the lanthanide series – 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 5d 1 • The pattern slightly changes with Ce – 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 5d 1 4

*f *

1 • Pr puts it back on track – 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4

*f *

3 – This is because 4

*f*

and 5

*d*

are close in energies

### Noble Gas Configurations

• Instead of writing entire core electron configuration of the noble gas, one can abbreviate it [NG] & write only valence e • Al: 1

*s*

2 2

*s*

2 2

*p*

6 3

*s*

2 3

*p x*

1 or [Ne]3

*s*

2 3

*p x*

1 • Ag:1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 9 or [Kr]5s 2 4d 9 • Am:1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4

*f *

14 5

*d*

10 6

*p*

6 7

*s*

2 5

*f *

7 or [Rn] 7

*s*

2 5

*f *

7 • Sg: [Rn]7

*s*

2 5

*f *

14 6

*d*

4 86+2+14+4 =106= Sb atomic#

### Orbital Notations

• • • • • This shows all 4 quantum numbers

*n *

(principle quantum #) = energy lvl 1,2,3...

*l m*

(angular momentum Q.N.) = shape (magnetic Q.N.) =

*x, y, z*

for

*p s,p,d,f *

, etc…

*s*

(spin Q.N.) = +1/2 (cw) or -1/2 (ccw) shown as upward or downward arrows 16 8 O ___ ___ ___ ___ ___ 1s 2s 2p x y z