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Atom video. http://www.youtube.com/watch?v=xqNSQ3OQMGI&feature=share. Basic Principle: electrons occupy lowest energy levels available. Aufbau Principle -- “Bottom Up Rule”. Stern-Gerlach Experiment. . . How could an orbital hold two electrons without electrostatic repulsion?.

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Presentation Transcript
atom video

Atom video

http://www.youtube.com/watch?v=xqNSQ3OQMGI&feature=share

slide2

Basic Principle:

electrons occupy lowest energy levels available

stern gerlach experiment
Stern-Gerlach Experiment

How could an orbital hold two electrons

without electrostatic repulsion?

Electron spin

spdf notation

2 ways to write electron configurations

spdf Notation

spdf NOTATION

for H, atomic number = 1

1

no. of

electrons

s

1

sublevel

value of energy level

Orbital Box Notation

ORBITAL BOX NOTATION

for He, atomic number = 2

Arrows show electron spin

(+½ or -½)

2



1s

1s

pauli exclusion principle
Example:

Determine the electron configuration and orbital notation for the ground state neon atom.

Pauli exclusion principle

An orbital can contain a maximum of 2 electrons,

and they must have the opposite “spin.”

write the ground state configuration and the orbital diagram for oxygen in its ground state
Write the ground state configuration and the orbital diagram for oxygen in its ground state

Hund’s Rule -

slide12

Basic Principle:

electrons occupy lowest energy levels available

Rules for Filling Orbitals

Bottom-up

(Aufbau’s principle)

Fill orbitals singly before doubling up

(Hund’s Rule)

Paired electrons have opposite spin

(Pauli exclusion principle)

slide13

Identify examples of the following principles:

1) Aufbau 2) Hund’s rule 3) Pauli exclusion

shorthand notation practice
Shorthand notation practice

Examples

●Aluminum: 1s22s22p63s23p1[Ne]3s23p1

● Calcium: 1s22s22p63s23p64s2

[Ar]4s2

● Nickel: 1s22s22p63s23p64s23d8

[Ar]4s23d8 {or [Ar]3d84s2}

● Iodine: [Kr]5s24d105p5 {or [Kr]4d105s25p5}

● Astatine (At): [Xe]6s24f145d106p5

{or [Xe]4f145d106s26p5}

[Noble Gas Core] + higher energy electrons

orbital energy ladder
Orbital energy ladder

f

d

n = 4

p

d

s

p

n = 3

s

p

n = 2

s

n = 1

Energy

s

slide18

Phosphorus

Symbol:P

Atomic Number:15

Full Configuration:1s22s22p63s23p3

Valence Configuration:3s23p3

Shorthand Configuration:[Ne]3s23p3













Box Notation













2s

1s

2p

3s

3p

slide19
Quantum numbers and orbital energiesEach electron in an atom has a unique set of quantum numbers to define it{ n, l, ml, ms }
  • n = principal quantum number
    • electron’s energy depends principally on this
  • l = azimuthal quantum number
    • for orbitals of same n, l distinguishes different shapes (angular momentum)
  • ml = magnetic quantum number
    • for orbitals of same n & l, ml distinguishes different orientations in space
  • ms = spin quantum number
    • for orbitals of same n,l & ml, ms identifies the two possible spin orientations
slide20
Energy levelSublevel# of orbitals/sublevel

n = 1 1s (l = 0) 1 (ml has one value)

n = 22s (l = 0) 1 (ml has one value)

2p (l = 1) 3 (ml has three values)

n = 33s (l = 0) 1 (ml has one value) 3p (l = 1) 3 (ml has three values) 3d (l = 2) 5 (ml has five values)

Quantum numbers and orbital energies Each atom’s electron has a unique set of quantum numbers to define it{ n, l, ml, ms }

n = principal

quantum

number

(energy)

l = azimuthal

quantum

number

(shape)

ml = magnetic

quantum

number

(orientation)

concept each electron in an atom has a unique set of quantum numbers to define it n l m l m s
Concept: Each electron in an atom has a unique set of quantum numbers to define it{ n, l, ml, ms }

21

quantum numbers unique set for each e
Quantum numbers: unique set for each e-
  • s orbitals p orbitals d orbitals f orbitals
  • l = 0 l = 1l = 2l = 3
  • ml = 0ml = -1, 0, 1ml = -2, -1, 0, 1, 2 ml=-3,-2,-1,0,1,2,3
  • An s subshellA p subshellA d subshell An f subshell
  • One s orbitalThree p orbitalsFive d orbitals Seven f orbitals
  • For n=1 l=0 an s subshell (with 1 orbital)
  • For n=2 l=0,1 an s subshell and a p subshell (with 3 orbitals)
  • For n=3 l=0,1,2 an s subshell, a p subshell, a d subshell (with 5 orbitals)
  • For n=4 l=0,1,2,3 an s subshell, a p subshell, a d subshell, an f subshell (with 7 orbitals)
electronic configuration of br
Electronic configuration of Br

1s2 2s22p6 3s23p63d10 4s24p5

[Ar]3d104s24p5

[Ar] = “noble gas core”

[Ar]3d10 = “pseudo noble gas core”

(electrons that tend not to react)

Atom’s reactivity is determined by valence electrons

valence e’s in Br:4s24p5

highest n electrons

slide24

Valence e- shells for

transition metalsv.main group elements

d orbitals not included

in valence shell

(pseudo noble gas cores)

d orbitals sometimes

included in valence shell

rule of thumb for valence electrons
Rule-of-thumb for valence electrons

Examples

●Sulfur: 1s22s22p63s23p4 or [Ne]3s23p4

valence electrons:3s23p4

● Strontium: [Kr]5s2

valence electrons:5s2

● Gallium: [Ar]4s23d104p1

valence electrons:4s24p1

● Vanadium: [Ar]4s23d3

valence electrons:4s2or3d34s2

Identify all electrons at the highest principal quantum number (n)

Use on exams,

but recognize

limitations

Use Table 8.9

for online HW

selenium s valence electrons
Selenium’s valence electrons

Written for increasing energy:

Pseudo noble gas core includes:

noble gas electron core

d electrons (not very reactive)

core and valence electrons in germanium
Core and valence electrons in Germanium

Written for increasing energy:

Pseudo noble gas core includes:

noble gas core

d electrons

d block some exceptions to the aufbau principle
d-block: some exceptions to the Aufbau principle

Fig. 8.9: Use this table for online homework

electron spin magnetism
Electron spin & magnetism

For the ground state oxygen atom:

spdf configuration:

orbital box notation:

Paramagnetic: atoms with unpaired electrons that are weakly attracted to a magnet.

Diamagnetic: atoms with paired electrons that are not attracted to a magnet.

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