Electron Electron Configuration!Configuration!

s, p, d, and fs, p, d, and f

The different sections of the Periodic The different sections of the Periodic Table are very important in understanding Table are very important in understanding Electron Configuration.Electron Configuration.There are 4 “Blocks” in the Periodic Table:There are 4 “Blocks” in the Periodic Table: the s-block, p-block, d-block, & f-block.the s-block, p-block, d-block, & f-block.

Remember the special rules for the d- and Remember the special rules for the d- and f- blocks:f- blocks: d – n-1d – n-1 f – n - 2f – n - 2

What do s, p, d, and f mean?What do s, p, d, and f mean?

These refer to the These refer to the sublevelssublevels within the within the principal quantum level (n).principal quantum level (n).

So, for n = 1, there is only one sublevel, s.So, for n = 1, there is only one sublevel, s.

n = 2, there are 2 sublevels: s & pn = 2, there are 2 sublevels: s & p

n = 3, there are 3 sublevels: s, p, & dn = 3, there are 3 sublevels: s, p, & d

So, within each level, there are n So, within each level, there are n sublevels.sublevels.

This shows the different blocks in the Periodic Table. This shows the different blocks in the Periodic Table.

It also shows in what order to write electron configurations It also shows in what order to write electron configurations (1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, (1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d,7p)5f, 6d,7p)

Block TableBlock Table

An ExampleAn Example

As - Arsenic As - Arsenic

1s1s22 2s 2s22 2p 2p66 3s 3s22 3p 3p66 4s 4s22 3d 3d1010 4p 4p33

The first number is which row it’s in, or the The first number is which row it’s in, or the principal quantum numberprincipal quantum number

The character is the block its in, which The character is the block its in, which refers to the refers to the sublevelsublevel

The superscript is the total number of The superscript is the total number of electrons in the electrons in the sublevelsublevel

A shortcut!A shortcut!1s1s

2s 2p2s 2p

3s 3p 3d3s 3p 3d

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

5s 5p 5d 5f5s 5p 5d 5f 5g5g

6s 6p 6d6s 6p 6d 6f6f 6g6g 6h6h

7s 7p7s 7p 7d7d 7f7f 7g7g 7h7h 7i7i

Do not exist in normal ground

state atoms

The Noble Gas The Noble Gas ConfigurationConfiguration

An obvious solution and An obvious solution and convenient short cut!convenient short cut!

Noble Gas ConfigurationNoble Gas ConfigurationThe Noble Gases are: The Noble Gases are: He, Ne, Ar, Kr, Xe, RnHe, Ne, Ar, Kr, Xe, Rn

Notice that each noble gas finishes a row, Notice that each noble gas finishes a row, or energy level.or energy level.Noble gas configurations take advantage Noble gas configurations take advantage of this by condensing what you have to of this by condensing what you have to write:write: Ex.Ex. He : He : 1s1s22

Ex. Ex. C : C : 1s1s22 2s 2s22 2p2 2p2Noble Gas Configuration for C: Noble Gas Configuration for C: [He][He] 2s 2s22 2p2 2p2

Noble Gas Config. – an exampleNoble Gas Config. – an example

The normal configuration for As-(Arsenic)The normal configuration for As-(Arsenic) 1s1s22 2s 2s22 2p 2p66 3s 3s22 3p 3p66 4s4s22 3d 3d1010 4p 4p33

Notice, the part in yellow is the same as Notice, the part in yellow is the same as Argon’s configuration: Argon’s configuration: 1s1s22 2s 2s22 2p 2p66 3s 3s22 3p 3p66 The noble gas configuration will start with The noble gas configuration will start with the gas in the row before it.the gas in the row before it. [Ar][Ar] 4s4s22 3d 3d1010 4p 4p33

It cuts down on a lot of writing, and that’s a It cuts down on a lot of writing, and that’s a good thing.good thing.

Add to back of second sheet!!Add to back of second sheet!!

OrbitalsOrbitals Each sublevel (s, p, d, f) contains orbitals.Each sublevel (s, p, d, f) contains orbitals. Remember, orbitals are electron-clouds that Remember, orbitals are electron-clouds that

hold the electrons 90% of the time.hold the electrons 90% of the time. Each orbital can hold TWO electrons, soEach orbital can hold TWO electrons, so

s - 2 electrons, 1 orbitals - 2 electrons, 1 orbital

p – 6 electrons, 3 orbitalsp – 6 electrons, 3 orbitals

d – 10 electrons, 5 orbitalsd – 10 electrons, 5 orbitals

f – 14 electrons, 7 orbitalsf – 14 electrons, 7 orbitals

Orbital DiagramsOrbital Diagrams

They’re Useful!They’re Useful!

The Aufbau PrincipleThe Aufbau Principle

Each electron occupies Each electron occupies the lowest energy the lowest energy orbitalorbital Electrons are Lazy!!!Electrons are Lazy!!!

All orbitals related to an All orbitals related to an energy level are of energy level are of equal energy.equal energy. Ex. The three 2p orbitals Ex. The three 2p orbitals

are the same energy are the same energy level.level.

All equivalent energy

Pauli Exclusion PrinciplePauli Exclusion Principle

A maximum of two A maximum of two electrons may occupy a electrons may occupy a single orbital, but single orbital, but only if only if the electrons have the electrons have opposite spins.opposite spins. Spin -- Electrons has an Spin -- Electrons has an

associated “spin,” either one associated “spin,” either one way or the other, like a top. way or the other, like a top.

These spins are called “spin These spins are called “spin up” and “spin down.”up” and “spin down.”

See example on board.See example on board.Box = orbital

Arrow = electron

Hund’s RuleHund’s Rule

Single electrons with Single electrons with the the samesame spin must spin must occupy each equal-occupy each equal-energy orbital energy orbital beforebefore additional electrons with additional electrons with opposite spins can opposite spins can occupy the occupy the samesame orbitals.orbitals. Electrons are Electrons are

UNFRIENDLYUNFRIENDLY Why?Why?

1s2 2s2 2p3

1s2 2s2 2p3

NOT

Ex. Nitrogen:

•1s2 2s2 2p3

The order of Things…The order of Things…

Electrons, being Electrons, being unfriendly, fill up the unfriendly, fill up the empty orbitals before empty orbitals before sharing orbitals.sharing orbitals. Similar to seats on a Similar to seats on a

bus – on a bus, you sit bus – on a bus, you sit alone, rather than with a alone, rather than with a stranger, if there is an stranger, if there is an option.option.

NpNp11

NpNp22

NpNp33

NpNp44

NpNp55

NpNp66

The Shapes of the s, p, and d OrbitalsThe Shapes of the s, p, and d OrbitalsSketch these at bottom of outlineSketch these at bottom of outline

F-Orbitals!F-Orbitals!

Do not bother sketching these—just notice Do not bother sketching these—just notice how STRANGE they are!how STRANGE they are!

If you want to see more, go to: http://www.orbitals.com/orb/orbtable.htm

Please write this at the bottom of your outlinePlease write this at the bottom of your outline

Orbital Shape No. per sublevel s Spherical 1 p Figure-8,

dumbbells 3

d Double figure-8s & drops with

coffee

5

f Don’t worry! 7

ee-- Config. and Orb. Diag. for Ions Config. and Orb. Diag. for Ions

What is an ion?What is an ion?

Examples of ions:Examples of ions: NaNa++

MgMg2+2+

FeFe3+3+

ClCl-- SS2-2-

I’ll do the configs. on I’ll do the configs. on the overhead.the overhead.

When writing electron When writing electron configurations or orbital configurations or orbital diagrams for ions it’s a diagrams for ions it’s a little harder because it little harder because it can look like a can look like a different different atom.atom.Just subtract the missing Just subtract the missing electrons or add the extra electrons or add the extra electronselectrons

Li+ (1s2 2s0)

He (1s2)