1sorbital

2sorbital

2porbitals

3sorbital

Nucleus

Electron energy levels have sublevels of different shapes

3 principlesdescribe theelectron configurationof any atom:• the aufbau principle• the Pauli exclusion principle• and Hund’s rule

Electron Configurations:location of e–’s in different orbitals

How do electrons fill these orbitals?

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Slide 3 of 20

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Electron Arrangement in Atoms

> Aufbau Principle:(building up)

e–’s fill orbitals of lowest energy first

nucleus

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Slide 4 of 20

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Electron Arrangement in Atoms

> Pauli Exclusion Principle:(up/down)

e–’s in same orbital have opposite spin

nucleus

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Slide 5 of 20

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Electron Arrangement in Atoms

> Hund’s Rule:(up/up/up/

down/down/down)e–’s pair after one in each same E orbital

nucleus

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Slide 6 of 20

End Show

2s21s2 3s23p32p6

Write the electron configuration for phosphorus (P):

nucleus

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Slide 7 of 20

End Show

Write the electron configuration for phosphorus (P):

nucleus

2s21s2 3s23p32p6

valence electrons:e–’s in the outer most (highest) energy level

How many valence e–’s in phosphorus (P)? 5

End Show

Slide 8 of 20

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Electron Arrangement in Atoms

>

nucleus

Write the electron configuration for Krypton (Kr):

2s21s2 2p6 3p63s2 4p64s2 3d10

(3d fills after 4s)

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Slide 9 of 20

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Electron Arrangement in Atoms

>

nucleus

Write the electron configuration for Krypton (Kr):

2s21s2 2p6 3p63s2 4p64s2 3d10

valence electrons:e–’s in the outer most (highest) energy level

How many valence e–’s in Krypton (Kr)? 8

4p12s21s2 2p6 3p63s2 4p14s23d10

OR 4s2[Ar] 3d10

Write the full electron configuration for Gallium (Ga), atomic number 31.

noble gas coreconfiguration Ar

Phosphorus (P):

Lewis dot diagram:valence e–’s as dots

[Ne]3s2 3p3

1s2 2s2 2p6 3s2 3p3

# valence e–’s: ___

Group # : ___

5

5A

PLewis dot diagram:

Bromine (Br):

[Ar]4s2 3d10 4p5

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5

# valence e–’s: ___

Group # : ___

7

7A

Lewis dot diagram: Br

valence e–’s:e–’s in highest energy level

1. Which element has following electron configuration: 1s2 2s2 2p6 3s2

A. Ca

B. Ne

C. Na

D. Mg

Quick Quiz!

How many valence e–’s? 2

Group 2

2. Write the electron configuration for an atom of oxygen (O).

A. 1s2 2s6

B. 1s2 2p6

C. 1s2 2s2 2p4

D. 1s2 2s3 2p3

Quick Quiz.

How many valence e–’s? 6

Group 16 (6A)

H , He

Li , Be

Na , Mg

B , C , N , O , F , Ne

Al , Si , P , S , Cl , Ar

s orbitalp orbitals