Unit 03

The Modern Atom

Quantum Mechanical Model

• Quantum mechanics was developed by Erwin Schrodinger

• Estimates the probability of finding an e- in a certain position

• Electrons are found in an “electron cloud” or orbital

Radial Distribution CurveOrbital

Orbital (“electron cloud”)

– Region in space where there is 90% probability of finding an e-

Each orbital letter has a different shape.

“s” orbital

spherical shapedspherical shaped1 orbital1 orbital

“p” orbitalDumbbell shapedDumbbell shaped

Arranged x, y, z axesArranged x, y, z axes3 orbitals 3 orbitals

“d” orbital

clover clover shapedshaped5 orbitals5 orbitals

“f” orbital

f

• Orbitals combine to form a spherical shape.

2s

2pz2py

2px

7 orbitals7 orbitals

Hog HiltonYou are the manager of a prestigious new hotel in downtown

Midland—the “Hog Hilton”. It’s just the “snort of the town” and you want to keep its reputation a cut above all the other hotels. Your problem is your clientele. They are hogs in the truest sense.

Your major task is to fill rooms in your hotel. The Hog Hilton only has stairs. You must fill up your hotel keeping the following rules in mind:1) Hogs are lazy, they don’t want to walk up stairs!2) Hogs want to room by themselves, but they would rather room with another hog than walk up more stairs.3) If hogs are in the same room they will face in opposite

directions.4) They stink, so you can’t put more than two hogs in each

room.

Hog Hilton• Your hotel looks like the diagram below:

6th floor ________5th floor ________ ________ ________ 4th floor ________3rd floor ________ ________ ________2nd floor ________1st floor ________

Book 7 hogs into the rooms.

Hog HiltonYour hotel looks like the diagram below:

6th floor ________

5th floor ________ ________ ________

4th floor ________

3rd floor ________ ________ ________

2nd floor ________

1st floor ________

Book 14 hogs into the rooms.

Choose 3 Days of the week and Draw them in the left side of your spiral.

6th floor ______5th floor ______ ______ ______ 4th floor ______3rd floor ______ ______ ______2nd floor ______1st floor ______

Hog Hilton

= ↑ = ↓

Let’s play Hog Hilton!!Let’s play Hog Hilton!!

Now you will relate the “Hog Hilton” to electron orbitals. Electron orbitals are modeled by the picture on the left and are grouped into principal energy levels.

1. Compare their similarities and differences.2. To go between floors on the Hog Hilton did the hogs need

to use energy? Would electrons need to use the energy to go between orbitals?

3d ___ ___ ___ ___ ___ n=3(4s ____) n=43p ___ ___ ___ n=33s ___ n=32p ___ ___ ___ n=22s ___ n=21s ___ n=1

6th floor ___5th floor ___ ___ ___4th floor ___3rd floor ___ ___ ___2nd floor ___1st floor ___

A. Rules for e- configurations

1. Aufbau principleAufbau principle: electrons fill the lowest energy orbitals first.

(Hogs are lazy, they don’t want to walk up stairs!)

A. Rules for e- configurations

2. 2. Pauli Exclusion principlePauli Exclusion principle: each orbital can hold TWO TWO electrons with opposite spins

(They stink, so you can’t put more than two hogs in each room. & If hogs are in the same room they will face in opposite directions.)

RIGHTWRONG

A. Rules for e- configurations3. 3. Hund’s ruleHund’s rule: within a sublevel, place one

e- per orbital before pairing them.

(Hogs want to room by themselves, but they would rather room with another hog than walk up more stairs.)

4p ___ ___ ___

3d ___ ___ ___ ___ ___

4s ___

3p ___ ___ ___

3s ___

2p ___ ___ ___

2s ___

1s ___

B. Drawing Orbitals

Krypton

↑↓↑↓↑ ↑ ↑↓ ↓ ↓↑↓↑ ↑ ↑↓ ↓ ↓↑↓↑ ↑ ↑↓ ↓ ↓ ↑↓ ↑↓↑ ↑ ↑↓ ↓ ↓

4p ___ ___ ___

3d ___ ___ ___ ___ ___

4s ___

3p ___ ___ ___

3s ___

2p ___ ___ ___

2s ___

1s ___

White Board Practice: Drawing Orbitals

Chlorine

↑↓↑↓↑ ↑ ↑↓ ↓ ↓↑↓↑ ↑ ↑↓ ↓

4p ___ ___ ___

3d ___ ___ ___ ___ ___

4s ___

3p ___ ___ ___

3s ___

2p ___ ___ ___

2s ___

1s ___

White Board Practice: Drawing Orbitals

Nickel

↑↓↑↓↑ ↑ ↑↓ ↓ ↓↑↓↑ ↑ ↑↓ ↓ ↓↑↓↑ ↑ ↑↓ ↓ ↓ ↑ ↑

C. Writing the Electron Configuration

4p _ ↑↓ _ _ ↑↓ _ _ ↑↓ _

3d _ ↑↓ _ _ ↑↓ _ _ ↑↓ _ _ ↑↓ _ _ ↑↓ _

4s _ ↑↓ _

3p _ ↑↓ _ _ ↑↓ _ _ ↑↓ _

3s _ ↑↓ _

2p _ ↑↓ _ _ ↑↓ _ _ ↑↓ _

2s _ ↑↓ _

1s _↑↓_ 1s2

Krypton: atomic number - 36

2s2 2p63s2 3p64s2 3d104p6

Add the exponents to check your answer

Exponent is number of e-

4p ___ ___ ___

3d ___ ___ ___ ___ ___

4s ___

3p ___ ___ ___

3s ___

2p ___ ___ ___

2s ___

1s ___

White Board Practice: Writing Electron Configurations

IronFe – atomic number 26

↑↓↑↓↑ ↑ ↑↓ ↓ ↓↑↓↑ ↑ ↑↓ ↓ ↓↑↓↑ ↑↓ ↑ ↑↑

2s2 2p63s2 3p64s2 3d61s2

Add the exponents to check your answer

4p ___ ___ ___

3d ___ ___ ___ ___ ___

4s ___

3p ___ ___ ___

3s ___

2p ___ ___ ___

2s ___

1s ___

White Board Practice: Writing Electron Configurations

SulfurS – atomic number- 16

↑↓↑↓↑ ↑ ↑↓ ↓ ↓↑↓↑ ↑ ↑↓

2s2 2p63s2 3p41s2

Add the exponents to check your answer

1s 2s 2p 3s 3p

___ ___ ___ ___ ___ ___ ___ ___ ___

Worksheet: Electron Configurations

Aluminum atomic number - 13

Al Electron Configuration:___________________

↑↓ ↑↓ ↑ ↑ ↑↓ ↓ ↓ ↑↓

2s2 2p63s2 3p11s2

↑

67

e- config. Periodic Patterns

1234567

spp

d (n d (n –– 1) 1)

f (n f (n –– 2) 2)

n = Principle energy level(Period #)

What is the electron configuration for Br? 1s2 2s2 2p6 3s2 3p6 4s23d10

Br

1234567

4p5

What is the electron configuration for Sulfur?

1s2 2s2 2p6 3s2 3p4

S

1234567

What is the electron configuration for Titanium?

1s2 2s2 2p6 3s2 3p6 4s23d2

Ti

1234567

What element has the electron configuration 1s22s22p63s23p4?

Add together all the exponents, then find that atomic number. = Sulfur 16

How many electrons are present in the d sublevel of a neutral atom of Manganese?

Learning Check

1 2 3 4 5

5 electrons

D. Noble Gases Shorthand

• Use the noble gas in the previous row.

• Write noble gas symbol in brackets then rest of the e-configuration.

Shorthand Configuration

S 16e-

1s22s22p63s23p4

Longhand Configuration

S 16e- [Ne]3s23p4

[Ne]3s3s22 3p2

Noble Gas ShorthandEx – Silicon

1234567

[Ar]4s4s223d104p2

Noble Gas Shorthand• Ex - Germanium

1234567

[Xe]6s6s11

Noble Gas Shorthand• Ex - Cesium

1234567

Learning Check

Use Noble Gas Shorthand write the e-

config. 1. Cr

2. Br

3. Sn

4. Ba

[Ar] 4s2 3d4

[Ar] 4s2 3d10 4p5

[Kr] 5s2 4d10 5p2

[Xe] 6s2

Learning Check

1. Which orbital quantum number combination is not possible?

A. 2s

B. 2d

C. 4d

D. 3p

2. How many electrons are required to fill the 1st energy level?

A. 2

B. 4

C. 8

D. 10

Learning Check

3. How many electrons are required to fill the 2nd energy level?

A. 2

B. 4

C. 8

D. 10

Learning Check

4. How many electrons are required to fill the 3rd energy level?

A. 4

B. 8

C. 10

D. 18

Learning Check

7s 7p 7d 7f6s 6p 6d 6f5s 5p 5d 5f4s 4p 4d 4f3s 3p 3d2s 2p1s

Correct orbital filling order

The trick to f orbitals!

Examples:

Erbium- Er 68

Hassium- Hs

[Xe] 6s24f115d1

[Rn] 7s25f146d6

Learning Check

Use Noble Gas Shorthand write the e- config.

1. Sm

2. Db

[Xe] 6s2 4f5 5d1

[Rn] 7s2 5f14 6d3

II. Quantum Numbers

UPPER LEVEL

• Four Quantum Numbers:

– Specify the “address” of each electron in an atom

1. Principal Quantum Number ( n )

– Energy level

– Size of the orbital

– n2 = # of orbitals in the energy level

II. Quantum Numbers

II. Quantum Numbers

s p d f

2. Angular Momentum Quantum # ( l )– Energy sublevel

– Shape of the orbital

0 1

23

II. Quantum Numbers

• n = # of sublevels per level

• n2 = # of orbitals per level

• Sublevel sets: 1 s, 3 p, 5 d, 7 f

Principal energy level (n)

Number of sublevels

Names of Sublevels

1st energy level 1 sublevel “s” (1 orbital)

2nd 2 sublevels “s” (1) & “p” (3 orbitals)

3rd 3 sublevels “s”(1) , “p” (3) & “d” (5 orbitals)

4th 4 sublevels “s”(1), “p”(3) , “d”(5), and “f” (7)

II. Quantum Numbers

3. Magnetic Quantum Number ( ml )

– Orientation of orbital

– Specifies the exact orbitalwithin each sublevel

II. Quantum Numbers

px py pz

II. Quantum Numbers

4. Spin Quantum Number ( ms )

– Electron spin +½ or -½

– An orbital can hold 2 electrons that spin in opposite directions.

+½ -½

II. Quantum Numbers

1. Principal #

2. Ang. Mom. #

3. Magnetic #

4. Spin #

energy level

sublevel (s,p,d,f)

orbital

electron

– No two electrons in an atom can have the same 4 quantum numbers.

– Each e- has a unique “address”:

A. Oxidation States

• Valence electrons – the outer electrons in an atom that are involved in chemical bonding

• Octet Rule - when forming compounds atoms want to have 8 e- (s2p6) like the noble gases (except He)

A. Oxidation States

• A “+” means lose electrons

• A “–” means gains electrons

• Determine the element’s behavior in the company of other elements

• Some elements only have one oxidation state, others have several

• The transition metals generally have several oxidation states

B. Justifying Oxidation States

• Metals lose e- to either minimize e- to e- repulsions or eliminative their valence e- entirely

• Nonmetals tend to gain electrons to acquire an octet of electrons – (8 valence e- arranged as ns2np6 where n = principle

energy level)– Noble gases have octet naturally

• Transition metals have oxidation state of +2 since they lose the s2 that was filled just before the d-sublevel began filling

• 3d e- are similar in energy to 4s e- & 4d are similar to 5s, etc.

Example 1:Sulfur have many oxidation states. Use an

orbital notation to justify its most common -2 oxidation state:

Sulfur is a nonmetal and tends to gain e- creating the -2 charge. Gaining 2 e- gives it an octet of 3s23p6.

B. Justifying Oxidation States

3s ___ 3p ___ ___ ___↑↓ ↑↓ ↑↑[Ne]

Example 2:

Copper has two common oxidation states, +2 and +1. Justify both oxidation states:

Cu has an ending e- conf. of 4s23d9. Start by drawing its orbital notation of the outermost, valence electrons.

Since Cu is a transition metal, the +2 oxidation state come from losing the 4s e-s leaving 4s03d9.

The +1 oxidation state for Cu come from transferring one of the s e-s to the d orbitals to fill that sublevel and then losing the remaining s e- to form 4s03d10.

B. Justifying Oxidation States

4s 3d

___ ___ ___ ___ ___ ___ ↑[Ar] ↑ ↑ ↑ ↑ ↑↑ ↑ ↑ ↑ ↑

7s 7p 7d 7f6s 6p 6d 6f5s 5p 5d 5f4s 4p 4d 4f3s 3p 3d2s 2p1s

1st Principle Energy Level – 1 sublevel

2nd Principle Energy Level – 2 sublevels

4p ___ ___ ___3d ___ ___ ___ ___ ___4s ___3p ___ ___ ___3s ___2p ___ ___ ___2s ___1s ___

s– 1 orbitalp – 3 orbitalsd – 5 orbitals

Principle Energy level – large number in frontSublevel – # and letter (orbital)

3rd Principle Energy Level – 3 sublevels

4th Principle Energy Level – 4 sublevels

Recap from yesterday