Electron Configurations The 2 nd address of the e -

Electron ConfigurationsElectron Configurations

The 2The 2ndnd address of the e address of the e--

Electron ConfigurationsElectron ConfigurationsElectron configurations are a list of all the Electron configurations are a list of all the

electrons in an atom (or ion).electrons in an atom (or ion).

Electrons are attracted to a nucleus. Electrons are attracted to a nucleus. They will move around the nucleus in They will move around the nucleus in predictable patterns. They will fill up predictable patterns. They will fill up available space inside the atom’s e- available space inside the atom’s e- cloud.cloud.

The Spaces allotted to electrons are The Spaces allotted to electrons are inside the energy levels and are sub-inside the energy levels and are sub-energy levels or orbitals named s, p, d, energy levels or orbitals named s, p, d, & f.& f.

SS sub-energysub-energy

Number ofNumber ofOrbitals in Orbitals in Sub-energySub-energylevellevel

Number of Number of electrons in electrons in sub-energy sub-energy levellevel

11 33 55

22 66 1010

77

1414

How many electrons can be in a sublevel?How many electrons can be in a sublevel?

A maximum of two electrons can be A maximum of two electrons can be placed in any one orbital.placed in any one orbital.

pp sub-energysub-energy

dd sub-energysub-energy

ff sub-energysub-energy

How do electronsHow do electrons

fill orbitals?fill orbitals?

Aufbau principleAufbau principle

To Build up….To Build up….

states that electrons states that electrons fill from the lowest fill from the lowest possible energy to possible energy to the highest energy the highest energy

Main energy level

n=1

n=2

n=3

n=4

2 e-

8 e-

18 e-

32 e-

1s

2s

3s

4s

2p

3p

4p

3d

4d

4f

2 e-

2 e-

2 e-

2 e-

6 e-

6 e-

6 e-

10 e-

10 e-

14 e-

ENERGY

Max # of e-

Sub-energy level e- per orbital

Electron ConfigurationsElectron Configurations

3p3p22

Energy LevelEnergy Level

SublevelSublevel

Number of Number of electrons in electrons in the sublevelthe sublevel

1s1s22 2s 2s22 2p 2p66 3s 3s22 3p 3p66 4s 4s22 3d 3d1010 4p 4p66 5s 5s22 4d 4d1010 5p 5p66 6s6s22 4f 4f1414…… etc.etc.

Diagonal RuleDiagonal Ruless

s 3p 3ds 3p 3d

s 2ps 2p

s 4p 4d 4fs 4p 4d 4f

s 5p 5d 5f 5g**s 5p 5d 5f 5g**

s 6p 6d 6f** 6g** 6h**s 6p 6d 6f** 6g** 6h**

s 7p 7d** 7f** 7g** 7h** 7i**s 7p 7d** 7f** 7g** 7h** 7i**

11

22

33

44

55

66

77

Steps:Steps:

1.1. Write the energy levels top to bottom.Write the energy levels top to bottom.

2.2. Write the orbitals in s, p, d, f order. Write Write the orbitals in s, p, d, f order. Write the same number of orbitals as the energy the same number of orbitals as the energy level.level.

3.3. Draw diagonal lines from the top right to the Draw diagonal lines from the top right to the bottom left.bottom left.

4.4. To get the correct order, To get the correct order,

follow the arrows!follow the arrows!

**By this point, we are past **By this point, we are past the current periodic table the current periodic table so we can stop.so we can stop.

Let’s Try It!Let’s Try It!Write the electron Write the electron configuration for the configuration for the following elements:following elements:

K, Zn, PbK, Zn, Pb

KK 1s1s22 2s 2s22 2p 2p66 3s 3s22 3p 3p66 4s 4s11

ZnZn 1s1s22 2s 2s22 2p 2p66 3s 3s22 3p 3p66 4s 4s22 3d 3d1010

PbPb 1s1s22 2s 2s22 2p 2p66 3s 3s22 3p 3p66 4s 4s22 3d 3d1010 4p 4p66 5s 5s22 4d4d1010 5p5p66 6s 6s22 4f 4f1414 5d 5d1010 6p 6p22

Shorthand Shorthand NotationNotation

We are only concerned We are only concerned about the outermost about the outermost electrons.electrons.

We can use the noble gases We can use the noble gases as a method to represent all as a method to represent all completely filled sub-energy completely filled sub-energy levels.levels.


Step 1: It’s the Showcase Showdown!Step 1: It’s the Showcase Showdown!Find the closest noble gas to the atom,Find the closest noble gas to the atom,WITHOUT GOING OVER the number WITHOUT GOING OVER the number of electrons in the atom of electrons in the atom Write the noble gas in brackets [ ].Write the noble gas in brackets [ ].

Step 2: Find where to resume by Step 2: Find where to resume by finding the next energy level. finding the next energy level.

Step 3: Start with that energy level Step 3: Start with that energy level and use the __sand use the __s22 Resume the Resume the configuration until it’s finished.configuration until it’s finished.


Chlorine Chlorine Longhand isLonghand is 1s1s22 2s 2s22 2p 2p66 3s 3s22 3p 3p55

You can abbreviate the first 10 electrons You can abbreviate the first 10 electrons with the noble gas, Neon.with the noble gas, Neon.

[Ne] replaces [Ne] replaces 1s1s22 2s 2s22 2p 2p66

3 is the next energy level after Ne So you3 is the next energy level after Ne So you start at level 3 with the diagonal rule start at level 3 with the diagonal rule (all levels start with s)(all levels start with s) Finish the Finish the configuration by adding 7 more econfiguration by adding 7 more e-- to total to total 1717

The Shorthand for Cl The Shorthand for Cl [Ne] 3s[Ne] 3s22 3p 3p55

Practice Shorthand NotationPractice Shorthand Notation Write the shorthand notation for Write the shorthand notation for

each of the following atoms:each of the following atoms:

Ca, I, BiCa, I, Bi

CaCa [Ar]4s[Ar]4s22

II [Kr]5s[Kr]5s22 4d 4d1010 5p 5p55

BiBi [Xe]6s[Xe]6s22 4f 4f1414 5d 5d1010 6p 6p33

Electron configuration of the Electron configuration of the elements of the first three elements of the first three

seriesseries

HOW ‘BOUT A SONG

TO HELP YOU FIGURE IT OUT!!

e- configuration e- configuration polkapolkaThere’s a little game that’s as easy as can There’s a little game that’s as easy as can

be, be,

With numbers & letters & lots of chemistry.With numbers & letters & lots of chemistry.

It comes from quantum theory & wave It comes from quantum theory & wave mechanic stuff, mechanic stuff,

But for now just learn the game & that will But for now just learn the game & that will be enough.be enough.

ee-- configuration configuration polkapolkaChorusChorus

1s1s22, 2s, 2s22 then comes 2p then comes 2p66,,

The e- configuration game is really slick.The e- configuration game is really slick.

From the alkali to halogen and on to noble gas,From the alkali to halogen and on to noble gas,

Now you can understand the Periodic Law at Now you can understand the Periodic Law at last.last.

e- configuration e- configuration polkapolka

Atoms have orbitals where eAtoms have orbitals where e-- like to play like to play

And those eAnd those e-- fill the orbitals in a special way. fill the orbitals in a special way.

It’s a “building up” process-you can learn it in a It’s a “building up” process-you can learn it in a second. second.

And you can call it “Aufbau” if Deutsch is what you And you can call it “Aufbau” if Deutsch is what you sprechen.sprechen.






e- configuration e- configuration polkapolka

The outermost e- in atoms have to be,The outermost e- in atoms have to be,

The most important ones for understanding The most important ones for understanding chemistry.chemistry.

These valence e- are shared, or lost or gained, These valence e- are shared, or lost or gained,

In chemical reactions when atoms rearrange.In chemical reactions when atoms rearrange.






ee-- configuration configuration polkapolka

But the joy is that now… in this point in history, But the joy is that now… in this point in history,

We can finally solve the periodic table mystery.We can finally solve the periodic table mystery.

Why do elements form families, what is the Why do elements form families, what is the explanation?explanation?

Their Their valence e-valence e- have the have the same configurationsame configuration..






Exceptions to the Aufbau Exceptions to the Aufbau PrinciplePrinciple

Chemistry wouldn’t be any fun if it didn’t Chemistry wouldn’t be any fun if it didn’t throw throw you a curve ball every now and you a curve ball every now and then.then.

Some Atoms break the rules because they Some Atoms break the rules because they can can exist in a configuration that maintains a exist in a configuration that maintains a

lower lower energy.energy. There are many exceptions, but the most There are many exceptions, but the most

common ones are atoms that end with a common ones are atoms that end with a

dd44 and d and d9 9 configuration. configuration.


dd44 is one electron short of being HALF full is one electron short of being HALF full↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑ __ __

In order to become more stable one of the In order to become more stable one of the closest sclosest s electrons will actually move over to electrons will actually move over to the the open dopen d orbital. orbital.

Ex.: Cr by rule would be [Ar] 4sEx.: Cr by rule would be [Ar] 4s22 3d 3d44

The Exception makes it, [Ar] 4sThe Exception makes it, [Ar] 4s11 3d3d55..

ProcedureProcedure:: Find the Find the closest sclosest s orbital. Steal 1 orbital. Steal 1 electron electron from it, and add it to the d. This from it, and add it to the d. This will create a ½ filled will create a ½ filled lowerlower energy, more energy, more stablestable configuration. configuration.


OK, so this helps the d, but what about the OK, so this helps the d, but what about the poor s orbital that loses an electron?poor s orbital that loses an electron?

Remember, half full is good… and when an s Remember, half full is good… and when an s loses 1, it too becomes half full!loses 1, it too becomes half full!

So… having the s half full and the d half full is So… having the s half full and the d half full is usually a lower energy configuration than usually a lower energy configuration than leaving the s full and the d sub-energy level leaving the s full and the d sub-energy level with one empty orbital.with one empty orbital.


dd99 is one electron short of being full is one electron short of being full

↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↑__

Just like dJust like d44, one of the , one of the closest sclosest s electrons will go into the d, this electrons will go into the d, this time making it dtime making it d1010 instead of d instead of d99..

Ex: Au by rule would be [Xe] 6sEx: Au by rule would be [Xe] 6s22 4f 4f1414 5d 5d99, ,

The exception makes it [Xe] 6sThe exception makes it [Xe] 6s11 4f 4f1414 5d 5d1010

ProcedureProcedure: Same as before! Find the closest s orbital. : Same as before! Find the closest s orbital. Steal Steal one electron from it, and add it to the d.one electron from it, and add it to the d.

Irregular confirmations of Cr and CuIrregular confirmations of Cr and Cu

Chromium steals a 4s electron to half fill its 3d sublevel

Copper steals a 4s electron to FILL its 3d sublevel

Try These ExceptionsTry These ExceptionsWrite the shorthand Write the shorthand notation notation for: for:

Cu, WCu, W

CuCu [Ar] 4s[Ar] 4s11 3d 3d1010

WW [Xe] 6s[Xe] 6s11 4f 4f1414 5d 5d55

Electron NotationsElectron Notations

The 3The 3rdrd address of the e address of the e--

Orbital DiagramsOrbital Diagrams Graphical representation of an Graphical representation of an

electron configurationelectron configuration

Arrows are used to represent electrons.Arrows are used to represent electrons.

The direction and position of each arrow The direction and position of each arrow identifies the spin and which orbital within aidentifies the spin and which orbital within a

sublevel an e- exists.sublevel an e- exists.

Same rules applySame rules apply 1.1. Aufbau principleAufbau principle

2.2. Pauli’s Exclusion principle Pauli’s Exclusion principle

3.3. Hund’s RuleHund’s Rule

Orbital DiagramsOrbital Diagrams

Hund’s RuleHund’s RuleIn orbitals of EQUAL In orbitals of EQUAL

ENERGY (p, d, and ENERGY (p, d, and f), electrons will f), electrons will fill in each orbital fill in each orbital before pairing up.before pairing up.

In In MonopolyMonopoly, you have to , you have to build houses EVENLY. You build houses EVENLY. You can not put 2 houses on a can not put 2 houses on a property until all the property until all the properties in the set have at properties in the set have at least 1 house.least 1 house.

LithiumLithiumLithiumLithium

Group 1AGroup 1A

Atomic number = 3Atomic number = 3

1s1s222s2s11 ---> 3 total electrons ---> 3 total electrons

..1s 2s

CarbonCarbonCarbonCarbon

Group 4AGroup 4A

Atomic number = 6Atomic number = 6

1s1s2 2 2s2s2 2 2p2p22

Here we see for the first Here we see for the first time time HUND’S RULEHUND’S RULE. . When placing electrons in When placing electrons in a set of orbitals having the a set of orbitals having the same energy, we place same energy, we place them singly without pairing them singly without pairing up.up.

..1s 2s 2p

Draw these orbital Draw these orbital diagrams!diagrams!

O, Cr, HgO, Cr, Hg

O = [He] O = [He] . . 2s 2p2s 2p

Cr = [Ar] Cr = [Ar] {Exception to Aufbau} {Exception to Aufbau} 4s 3d4s 3d

Hg = [Xe] Hg = [Xe] 6s 4f 5d6s 4f 5d

Quantum NumbersQuantum Numbers

The Final address of the eThe Final address of the e--

The zip code of the electron!The zip code of the electron!


Describe the location of electrons in an atomDescribe the location of electrons in an atom

1) 1) nn – – principalprincipal (energy level) (energy level)

2)2) l l – – azimuthalazimuthal (energy sublevel) (energy sublevel)

3) 3) mm – – magneticmagnetic (orbital) (orbital)4)4) s s – – spinspin (direction of electron spin) (direction of electron spin)

No two electrons in the same atom can have No two electrons in the same atom can have the same set of all four quantum numbers!the same set of all four quantum numbers!

Assigning the NumbersAssigning the Numbers

The three quantum numbers (n, l, and m) are integers. The principal quantum number (n) cannot be zero.

n must be 1, 2, 3, etc. The angular momentum quantum number (l) can be any integer between 0 and n - 1.

Ex. For n = 3, l can be either 0, 1, or 2.

The magnetic quantum number (m) can be any integer between -l and +l.

Ex. For l = 2, m can be either -2, -1, 0, +1, or +2.

Quantum Quantum NumbersNumbers

What are the quantum What are the quantum numbers of the numbers of the

last electronlast electron placed placed on Aluminum.on Aluminum.

Quantum NumbersQuantum Numbers The StepsThe Steps

1. Write out e- configurations for the element.1. Write out e- configurations for the element.

2. Determine the e- notations for the 2. Determine the e- notations for the element. element. Identify the last placed e-Identify the last placed e-

Example:Example: Al Al 1s 1s22, 2s, 2s22, 2p, 2p66, 3s, 3s22, 3p, 3p11

AlAl [Ne] [Ne] ↑↓ ↑↓ ↑↑__ __ __ __ __ 3s 3p 3s 3p

Last placed electron

Quantum NumbersQuantum Numbers3. Identify each quantum number for 3. Identify each quantum number for the the

last e- placed last e- placed in the highest energy orbital.in the highest energy orbital.

nn the energy level of the e- the energy level of the e- nn = 1,2,3,..7 = 1,2,3,..7 ll the sub-energy of the e- the sub-energy of the e- l l = {s = 0, p=1, d=2, = {s = 0, p=1, d=2,

f=3}f=3} mm the specific orbital in which the e- is located. the specific orbital in which the e- is located.

(Treat as a number line) (Treat as a number line)

mm = = 0 0 -1 -1 00 +1+1 -2-2 -1 -1 00 +1+1 +2+2 -3-3 -2-2 -1-1 00 +1+1 +2+2 +3+3

s p d fs p d f ss The specific e- in the orbital. The specific e- in the orbital. ss = +½ for 1 = +½ for 1stst e- (up e- (up

arrow)arrow) ss = -½ for 2 = -½ for 2ndnd e- (down e- (down

arrow)arrow)

Quantum NumbersQuantum Numbers -1 0 +1-1 0 +1

Ex.: Ex.: AlAl [Ne] [Ne] ↑↓ ↑↓ ↑↑__ __ __ __ __

3s 3s 33pp

Al Al Last placed e- has the quantum Last placed e- has the quantum #s #s

nn = = 33 , , ll = = 11, , mm = = -1-1, , ss = = +½+½

Quantum NumbersQuantum Numbers Determine the Quantum # for these Determine the Quantum # for these

elements. elements.

Mg, Zn, and KrMg, Zn, and Kr

Mg Mg [Ne] 3s [Ne] 3s2 2 3, 0, 0, -½ 3, 0, 0, -½

Zn Zn [Ar] 4s [Ar] 4s22, 3d, 3d1010 3,2,2, -½ 3,2,2, -½

Kr Kr [Ar] 4s [Ar] 4s22, 3d, 3d10, 10, 4p4p66

4, 1, 1,-½ 4, 1, 1,-½


Try to name these elements!!Try to name these elements!!

A)A) 3, 1, -1, -½ 3, 1, -1, -½

3p3p44 Sulfur Sulfur

B)B) 4, 1, 0, +½ 4, 1, 0, +½

4p4p22 Germanium Germanium

c)c) 3, 2, -2, -½3, 2, -2, -½

3d3d66 Iron Iron

Documents

Electron Configurations The 2 nd address of the e -