For Mini-quiz 31

s d p

3d4d5d

6d

He is s not p

IN-CLASS EXERCISES : COMPLETE ELECTRONIC CONFIGURATIONS (Doing the `Aufbau’=building up)

IN –CLASS EXERCISE CHEM 11141. Write the complete electron configuration for the

elements below

a) Cl

b) K

c) Mn

d) Se

1s2 2s2 2p6 3s2 3p5

1s2 2s2 2p6 3s2 3p6 4s1

1s2 2s2 2p6 3s2 3p6 4s2 3d5

1s2 2s2 2p6 3s2 3p6 4s2 3d104p4

Which configuration is incorrect below ?(Use your Periodic Tables to figure out)A. 1s22s23s1

B. 1s22s22p3

C. 1s22s22p63s2

D. 1s22s2 2p63s23p5

1s22s2

3s1

1s22s2

2p3

1s22s2

2p63s2

1s22s2

2p63s23p5

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What is the correct complete electronic configuration for Ca?

A.1s22s22p63s23p6

B.1s22s22p63s2

C.1s22s22p63s23p64p1

D.1s22s22p63s23p64s2

1s22s2

2p63s23p6

1s22s2

2p63s2

1s22s2

2p63s23p64p1

1s22s2

2p63s23p64s2

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1s2 2s2 2p6 3s2 3p5

Abbreviated Configurations

Complete configuration for Cl

=[Ne] `core’

=Outermost `valence’ shell

[Ne] Valence shellAbbreviated configuration for Cl

[Ne] 3s23p5

Write the abbreviated electron configurations for the elements below, assuming Periodic Table arrangement for filling

a) Ca

b) Al

c) As

[Ar] 4s2

[Ne] 3s2 3p1

[Ar] 4s2 3d10 4p3

What is the correct, abbreviated configuration for Mg ?A. [Na]3s2

B.[He][Ne]3s2

C. [Ne]3s2

D.[He]2s22p63s2

[Na]3s2

[He][N

e]3s2

[Ne]3s2

[He]2

s22p63s2

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d electron variations

Mn

1) s d electron configuration switching

[Ar] 4s2 3d5 [Ar] 3d5 4s2

[Ar] 3d5

From spectra of atomized elements

As it behaves chemically in solution

Mn 2+

Evidenced by fact that all transition metals have a stable 2+ state… => outer 4s2 are removed first

Example: behavior of Mn

2.3. Write the correct, abbreviated d-switched configurations for the transition metals below

a) Cu

b) Fe 2+

c) Zn 2+

[Ar] 3d9 4s2 (3d and 4s switch order)

[Ar] 3d6 (outer 4s electrons lost first)

[Ar] 3d10 (outer 4s electrons lost first)

Which is the correct, abbreviated d-switched configuration for Cr

A.[Ar] 4s23d4

B.[Ar]4s24d2

C.[Ar]4s23d2

D.[Ar]4s24d4

[Ar]

4s23d4

[Ar]4

s24d2

[Ar]4

s23d2

[Ar]4

s24d4

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2) s and d undergo filled/half-filled/empty rearrangementsCr+1

[Ar] 3d4 4s1 [Ar] 3d5 4s0

STILL WRONG

RIGHT based on chemistry and spectroscopy

[Ar] 4s2 3d3 Periodic Table predicts

Corrected for chemistry by d-

switching

d-electron variations (continued)

Pigeonhole1 representation of electrons

[Ar] 3d4 4s1Cr+ =

As implied by Table + chemical reversal

4s 3dPigeonhole representation

D switch rule: s and d electrons in valence shell move around to produce filled, half-filled and/or empty orbitals in order to attain a more stable atom.

Corrected for filled,half-filled, empty rule

[Ar]3d5 4s0

*This final moving around applies only for transition metals

After fill, half-filled, empty correction

1Called orbital diagrams in text

[Ar]

[Ar]

d switch rule: s and d electrons in valence shell move around to produce filled, half-filled and/or empty orbitals in order to attain a more stable atom.

If element only has s and p….it means no switching….