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Electrons in Atoms- Electrons in Atoms- Quantum MechanicsQuantum Mechanics
Why it matters- chemical reactions Why it matters- chemical reactions (making and breaking chemical bonds) (making and breaking chemical bonds) can be explained almost entirely based on can be explained almost entirely based on electrons in atoms and moleculeselectrons in atoms and molecules
A detailed understanding of where A detailed understanding of where electrons are in atoms allows us to do thiselectrons are in atoms allows us to do this
Start out with a short review of history of Start out with a short review of history of knowledge of atomic structure (see that knowledge of atomic structure (see that unit for detailed information)unit for detailed information)
What the great ones said…What the great ones said…
““I do not like it, and I am sorry I ever had I do not like it, and I am sorry I ever had anything to do with it. “anything to do with it. “ Erwin Schrödinger, speaking of quantum mechanics , speaking of quantum mechanics
““I think it is safe to say that no one understands I think it is safe to say that no one understands quantum mechanics. “quantum mechanics. “ Richard Feynman
““If that turns out to be true, I'll quit physics.” If that turns out to be true, I'll quit physics.” Max von Laue, , Nobel Laureate 1914, ,
(this gives us something to look forward to)(this gives us something to look forward to)
Early modelsEarly models
Democritus (~ 2500 Democritus (~ 2500 years ago)years ago)
Dalton (~ 1840)Dalton (~ 1840)
ThomsonThomson
ElectronsElectrons The Plum Pudding The Plum Pudding
ModelModel
RutherfordRutherford
The nucleus (Gold The nucleus (Gold Foil Experiment)Foil Experiment)
BohrBohr
The Planetary ModelThe Planetary Model
PlanckPlanck
Energy is quantized- an electron in an Energy is quantized- an electron in an atom is only “allowed” to have certain atom is only “allowed” to have certain amounts of energy, or to be at certain amounts of energy, or to be at certain distances from the nucleus- not in distances from the nucleus- not in betweenbetween
Quantized?Quantized?
An electron can only have certain
“allowed energies” no in-between
values can exist. continuous quantized
The Modern ViewThe Modern View
Electron Cloud ModelElectron Cloud Model
Major Contributors to the Modern Major Contributors to the Modern View of Atomic StructureView of Atomic Structure
Heisenberg-Heisenberg- Developed the “uncertainty principle” Developed the “uncertainty principle”
this says that it is impossible to know both the exact location this says that it is impossible to know both the exact location and motion of an electron at the same time. and motion of an electron at the same time.
This is not something that can be fixed with better equipment This is not something that can be fixed with better equipment or experiments- there are limits to what we can know about the or experiments- there are limits to what we can know about the detailed structure on an atom. detailed structure on an atom.
HeisenbergHeisenberg
SchrodingerSchrodinger
Wrote a “wave Wrote a “wave equation” that when equation” that when solved gave the likely solved gave the likely location of the location of the electrons in an atom- electrons in an atom- not an exact answer not an exact answer but likely (or high but likely (or high probability region in probability region in space).space).
The equationThe equation
What matters to us is that when this equation is solved, the answer gives a set of probabilities as to the likely location of the electron.This solution is a set of numbers known as “quantum numbers” andcollectively they describe the high probability regions around thenucleus where the electron is allowed and will most likely be,
And Einstein?And Einstein?
Explained the photoelectric effect- an Explained the photoelectric effect- an observation that when light of certain observation that when light of certain frequencies is shined on a metal, the metal frequencies is shined on a metal, the metal “ejects” an electron. “ejects” an electron.
Einstein never really believed that quantum Einstein never really believed that quantum mechanics was correct ---he was wrong on this mechanics was correct ---he was wrong on this oneone
What are the quantum numbers?What are the quantum numbers?
They are a set of solutions to equations They are a set of solutions to equations that give the most likely location of that give the most likely location of electrons in an atomelectrons in an atom
They do not give exact answers as that is They do not give exact answers as that is not possiblenot possible
Energy levelEnergy level
The first quantum number is the energy The first quantum number is the energy level or principal quantum numberlevel or principal quantum number
This corresponds mostly to the distance This corresponds mostly to the distance from the nucleusfrom the nucleus
Higher energy levels are located at a Higher energy levels are located at a greater distance from the nucleusgreater distance from the nucleus
Energy levels have values of 1,2,3..etcEnergy levels have values of 1,2,3..etc
Energy sublevelEnergy sublevel
An electron’s location within an energy An electron’s location within an energy level can be described in more detail by level can be described in more detail by giving its “sublevel”, which describes the giving its “sublevel”, which describes the shape of the region within the energy level shape of the region within the energy level where the electron is likely to be foundwhere the electron is likely to be found
Each energy level is allowed to have only Each energy level is allowed to have only specific sublevelsspecific sublevels
Sublevels cont’dSublevels cont’d
The first energy level has only one The first energy level has only one sublevel ssublevel s
The second energy level is only allowed to The second energy level is only allowed to have two sublevels s and phave two sublevels s and p
The third energy levels is only allowed to The third energy levels is only allowed to have s, p, and d sublevelshave s, p, and d sublevels
The fourth energy levels only has s, p, d, The fourth energy levels only has s, p, d, and f sublevelsand f sublevels
OrbitalsOrbitals
Each sublevel (s,p,d, Each sublevel (s,p,d, or f) can have a or f) can have a specific direction or specific direction or orientation. orientation.
We describe this by We describe this by saying that each saying that each sublevel has a sublevel has a specific number of specific number of orbitalsorbitals
Energy Energy subsublevellevel
# orbitals# orbitals
ss 11
pp 33
dd 55
ff 77
What are the orbitals?What are the orbitals?
Orbitals are what we say “hold” the Orbitals are what we say “hold” the electronselectrons
We often draw them as boxes or circles for We often draw them as boxes or circles for short but they are just mathematical short but they are just mathematical descriptions of regions in space where descriptions of regions in space where electrons have a high probability of being electrons have a high probability of being at any momentat any moment
OrbitalsOrbitals
Each orbital “holds” a maximum of two Each orbital “holds” a maximum of two electronselectrons
An orbital may be empty, have one An orbital may be empty, have one electron in it or have two electrons in itelectron in it or have two electrons in it
Electrons are like little tops spinning Electrons are like little tops spinning (opposite directions)(opposite directions)
SpinSpin
It is easier to use It is easier to use arrows than to draw arrows than to draw spinning tops so we spinning tops so we need one more rule need one more rule so that we can draw so that we can draw models of electrons in models of electrons in orbitalsorbitals
The Pauli Exclusion The Pauli Exclusion principleprinciple
Pauli Exclusion PrinciplePauli Exclusion Principle
An orbital may have at most two electrons An orbital may have at most two electrons and then only if the electrons have and then only if the electrons have opposite spinsopposite spins
Empty orbitalOne electron
(allowed) 2 electrons with opposite
spins(allowed)
One electron(allowed) 2 electrons
with thesame spin
(notallowed)
2 electrons with the
same spin(not
allowed)
Orbital shapesOrbital shapes
Recognize s,p,d,f shapesRecognize s,p,d,f shapes - it helps to know that there is a single s - it helps to know that there is a single s
orbital, 3 p orbitals, 5 d orbitals and 7 f orbital, 3 p orbitals, 5 d orbitals and 7 f orbitalsorbitals
Be able to sketch s and p shapesBe able to sketch s and p shapes
s orbitals orbital
Shaped like a sphere- Shaped like a sphere- each energy level has each energy level has an s orbitalan s orbital
p orbitalsp orbitals
Energy levels 2Energy levels 2 have a p sublevel, A p have a p sublevel, A p sublevel has three p orbitalssublevel has three p orbitals
They all have the same shape, just different They all have the same shape, just different orientations (directions)orientations (directions)
d orbitalsd orbitals
Energy levels 3Energy levels 3 have d sublevels, each of which has have d sublevels, each of which has 5 orbitals. They don’t look the same to you and I, but 5 orbitals. They don’t look the same to you and I, but they are equivalent mathematically (trust me on this)they are equivalent mathematically (trust me on this)
A summaryA summaryEnergy LevelEnergy Level sublevelssublevels orbitalsorbitals electronselectrons
11 ss 11 22
22 ss 11 22
pp 33 66
33 ss 11 22
pp 33 66
dd 55 1010
44 ss 11 22
pp 33 66
dd 55 1010
ff 77 1414
#sublevels#sublevels # e# e
11 22
22 88
33 1818
44 3232
OrOr For an energy level nFor an energy level n
There are n sublevelsThere are n sublevels nn22 orbitals orbitals 2n2n22 electrons electrons
In that particular energy levelIn that particular energy level Check on that:Check on that: E level 3 has:E level 3 has:
3 sublevels (s,p,d)3 sublevels (s,p,d) 9 orbitals (1 s, 3 p and 5 d)9 orbitals (1 s, 3 p and 5 d) 18 electrons s =2, p =6, d = 10)18 electrons s =2, p =6, d = 10)
Try n = 2 and 4 to get some extra practice.Try n = 2 and 4 to get some extra practice.
So what do we do with all this? So what do we do with all this?
We can write out ways to describe the We can write out ways to describe the most likely location of electrons in an atommost likely location of electrons in an atomWe can show a detailed model with circles We can show a detailed model with circles
and arrows (representing orbitals and and arrows (representing orbitals and electrons)- an electron orbital filling diagramelectrons)- an electron orbital filling diagram
Or we can use a shorter method- an electron Or we can use a shorter method- an electron configurationconfiguration
How we’ll do thisHow we’ll do this
You have the “Aufbau Diagram” on a You have the “Aufbau Diagram” on a separate handoutseparate handout
Watch a few examples- after we’ve done a Watch a few examples- after we’ve done a few together you’ll start to see some few together you’ll start to see some patternspatterns
The order goes…The order goes…7s7s6p6p5d5d4f4f6s6s5p5p4d4d5s5s4p4p3d3d4s4s3p3p3s3s2p2p2s2s1s1s
The orderThe order
You always start “plugging in electrons” at the You always start “plugging in electrons” at the lowest possible energy level (1,2,3 etc.) and lowest possible energy level (1,2,3 etc.) and sublevel (s,p,d,f…). sublevel (s,p,d,f…).
The order is specified on the diagram and does The order is specified on the diagram and does not change, unless there is a specific reason not change, unless there is a specific reason (maybe an exception cover later on)(maybe an exception cover later on)
Each represents an orbital and each orbital Each represents an orbital and each orbital can have up to two electrons in it- but only if can have up to two electrons in it- but only if they have opposite spins (Pauli Exclusion they have opposite spins (Pauli Exclusion Principle) Principle)
Let’s try someLet’s try someHydrogen- a hydrogen atom has only one Hydrogen- a hydrogen atom has only one
electron and it is most likely to be found in electron and it is most likely to be found in the lowest possible energy level and the lowest possible energy level and sublevel- 1s with one electronsublevel- 1s with one electron
The filling diagram would show the figure The filling diagram would show the figure below and we could also write a shorthand below and we could also write a shorthand of of 11ss11 which says that hydrogen has which says that hydrogen has 1 1 electronelectron in the in the first energy levelfirst energy level in the in the s s sublevelsublevel. We’d read this “one s one”. We’d read this “one s one”
1s
HeliumHelium
Helium has two electron- since an orbital Helium has two electron- since an orbital can hold up to two electrons, both of the can hold up to two electrons, both of the electrons for helium are in the first energy electrons for helium are in the first energy level, s sublevel, but with opposite spins level, s sublevel, but with opposite spins (Pauli exclusion principle). This is shown (Pauli exclusion principle). This is shown below. We’d write a below. We’d write a configurationconfiguration of 1s of 1s22..
1s
LithiumLithiumLithium has three electrons. We can put Lithium has three electrons. We can put
two of them in the first energy level, s two of them in the first energy level, s sublevel, but then that orbital is filled up. sublevel, but then that orbital is filled up. The next lowest orbitals are 2The next lowest orbitals are 2ndnd energy energy level, s sublevel (look at the Aufbau level, s sublevel (look at the Aufbau diagram). We put two in the 1s and the diagram). We put two in the 1s and the next one in the 2s. 1snext one in the 2s. 1s222s2s11. We’d say “one s . We’d say “one s two, 2 s one.”two, 2 s one.”
2s2s1s1s
BerylliumBeryllium
Four electrons- the first two go in 1s, then Four electrons- the first two go in 1s, then that is filled, the next two can go in two s.that is filled, the next two can go in two s.
The configuration is 1sThe configuration is 1s222s2s22. The filling . The filling diagram is shown below.diagram is shown below.
2s2s
1s 1s
On to BoronOn to Boron Boron has five electrons. We will now add to Be. Boron has five electrons. We will now add to Be.
This is why it is called the “building up principle.” This is why it is called the “building up principle.” The first two go in 1s, then the next two The first two go in 1s, then the next two electrons go in 2s and the next available location electrons go in 2s and the next available location is 2p. is 2p.
If you don’t have your filling order diagram If you don’t have your filling order diagram (Aufbau Diagram) this can be hard to see. The (Aufbau Diagram) this can be hard to see. The picture is on the next slide. picture is on the next slide.
The configuration (shorthand) will be The configuration (shorthand) will be 1s1s222s2s222p2p11..
Notice how the little 2’s and 1 add to Notice how the little 2’s and 1 add to 55, the , the number of electrons number of electrons
Filling DiagramFilling Diagram
2p2p2s2s1s1s
The orbital diagram places the p orbitalsa little off to the right only to make things less cluttered.By convention if there is onlyone electron in an orbital, wetreat it as spin +1/2 or spin up.
CarbonCarbon Here we have another electron and we will have Here we have another electron and we will have
a choice. We could place the sixth electron a choice. We could place the sixth electron either in the orbital that already has an electron either in the orbital that already has an electron or in an empty orbital.or in an empty orbital.
Hund’s RuleHund’s Rule says that as much as possible, says that as much as possible, electrons are “split” or kept unpaired.electrons are “split” or kept unpaired.
““seats on the bus” analogy.seats on the bus” analogy. The configuration will be The configuration will be 1s1s222s2s222p2p22. The . The
configuration is easier to write but has less configuration is easier to write but has less detail. Shortcuts are like that. The superscript detail. Shortcuts are like that. The superscript “2”s are not exponents- just a shorthand “2”s are not exponents- just a shorthand notation.notation.
CarbonCarbon
2p2p2s2s1s1s
NitrogenNitrogen
First the filling diagram, then the explanationFirst the filling diagram, then the explanation
2p 2p
2s2s
1s1s
NitrogenNitrogen
We still have “room” in the 2p sublevel.We still have “room” in the 2p sublevel.The electron can be unpaired by placing The electron can be unpaired by placing
one electron in each of the 3 p orbitals. one electron in each of the 3 p orbitals. They are labeled 2pThey are labeled 2pxx,2p,2pyy and 2p and 2pzz so an so an
extremely detailed configuration would be:extremely detailed configuration would be:1s1s222s2s22pp2p2pxx
112p2pyy112p2pzz
11. We usually just go . We usually just go
1s1s222s2s222p2p33
OxygenOxygen
We now will continue to add electrons to We now will continue to add electrons to the 2p sublevels but the next one must the 2p sublevels but the next one must “double up.” The configuration will be:“double up.” The configuration will be:
1s1s222s2s222p2pxx222p2pyy
112p2pzz11. Or 1s. Or 1s222s2s222p2p44..
The filling diagram is shown on the next The filling diagram is shown on the next slide.slide.
OxygenOxygen
2p2p
2s2s
1s1s
FluorineFluorine
I suspect you’re getting the hang of this by I suspect you’re getting the hang of this by now. The next available place for electrons now. The next available place for electrons is in the 2p orbital.is in the 2p orbital.
We could use either of the two orbitals that We could use either of the two orbitals that is not filled but we almost always go left is not filled but we almost always go left top right (and up first).top right (and up first).
1s1s222s2s222p2p55..See the “building up” idea yet?See the “building up” idea yet?
FluorineFluorine
2p2p
2s2s
1s1s
NeonNeon
Notice how we are now at the end of the Notice how we are now at the end of the second period (or row) on the table.second period (or row) on the table.
Notice how we are now about to fill up the Notice how we are now about to fill up the second energy level.second energy level.
This is not a coincidence!This is not a coincidence!The configuration is 1sThe configuration is 1s222s2s222p2p66. . Can you see where we will be going on Can you see where we will be going on
the filling diagram next- a new row on the the filling diagram next- a new row on the table and a new energy level.table and a new energy level.
NeonNeon
2p2p2s2s1s1s
SodiumSodium
By know we have filled up the entire By know we have filled up the entire second energy level (2s and 2p sublevels).second energy level (2s and 2p sublevels).
The next lowest energy orbitals are 3s The next lowest energy orbitals are 3s orbitals. orbitals.
The configuration will be 1sThe configuration will be 1s222s2s222p2p663s3s11..Filling diagram is on the next pageFilling diagram is on the next page
SodiumSodium
3s3s
2p2p
2s2s
1s1s
Magnesium and aluminumMagnesium and aluminum
Magnesium will fill up the 3s orbital and Magnesium will fill up the 3s orbital and have a configuration of 1shave a configuration of 1s222s2s222p2p663s3s22..
(You can draw the filling diagram yourself).(You can draw the filling diagram yourself).Aluminum- After we use the 3s sublevel Aluminum- After we use the 3s sublevel
we go to the next available energy level we go to the next available energy level and sublevels which are the 3p orbitals. and sublevels which are the 3p orbitals. We’ll fill them in using the same idea as We’ll fill them in using the same idea as we did for B through Ne (we’ll do a few but we did for B through Ne (we’ll do a few but not all).not all).
AluminumAluminum
3p3p
3s3s
2p2p
2s2s
1s1s
PhosphorousPhosphorous
Phosphorous has 15 electrons. We fill in Phosphorous has 15 electrons. We fill in all the orbitals from 1s through 32 and all the orbitals from 1s through 32 and then have three for the 3p orbitals- Using then have three for the 3p orbitals- Using Hund’s Rule they are “split or unpaired”Hund’s Rule they are “split or unpaired”
The orbital filling diagram is shown on the The orbital filling diagram is shown on the next slide.next slide.
PhosphorousPhosphorous
3p3p
3s3s
2p2p
2s2s
1s1s
ArgonArgon
It is no coincidence that Argon is the It is no coincidence that Argon is the element at the end of the 3element at the end of the 3rdrd period (row) period (row) and the end of the third energy leveland the end of the third energy level
The configuration is The configuration is 1s1s222s2s222p2p663s3s223p3p66..
ArgonArgon
3p3p
3s3s
2p2p
2s2s
1s1s
Potassium & CalciumPotassium & Calcium
We have no filled up all of the orbitals in We have no filled up all of the orbitals in energy levels 1, 2 and 3. The next energy levels 1, 2 and 3. The next available (lowest energy) sublevel is 4savailable (lowest energy) sublevel is 4s
Potassium (the first element on the 4Potassium (the first element on the 4thth row row of the table) has a configuration ofof the table) has a configuration of
1s1s222s2s222p2p663s3s223p3p664s4s11 and Calcium is and Calcium is1s1s222s2s222p2p663s3s223p3p664s4s22
Calcium’s filling diagram is on the next Calcium’s filling diagram is on the next slide.slide.
CalciumCalcium
4s 4s
3p3p
3s3s
2p2p
2s2s
1s1s
ScandiumScandium
When we fill in electrons for the transition When we fill in electrons for the transition metals we start using the d orbitals- there metals we start using the d orbitals- there are 5 d orbitals in any sublevel, and are 5 d orbitals in any sublevel, and collectively they can hold 10 electrons.collectively they can hold 10 electrons.
Hund’s rule (unpair as much as possible) Hund’s rule (unpair as much as possible) still appliesstill applies
After 4s, the next available sublevel is 3d After 4s, the next available sublevel is 3d so Sc will have a configuration of so Sc will have a configuration of
1s1s222s2s222p2p663s3s223p3p664s4s223d3d11..
ScandiumScandium
3d3d
4s4s
3p3p
3s3s
2p2p
2s2s
1s1s
IronIron
Iron has 26 total electrons so there are 6 Iron has 26 total electrons so there are 6 electrons in the 3d sublevelelectrons in the 3d sublevel
The configuration is 1sThe configuration is 1s222s2s222p2p663s3s223p3p664s4s223d3d66
IronIron
3d3d4s4s3p3p3s3s2p2p2s2s1s1s
ZincZinc
1s1s222s2s222p2p663s3s223p3p664s4s223d3d1010
3d3d4s4s3p3p3s3s2p2p2s2s1s1s
Summary so farSummary so far
To describe the most likely location of To describe the most likely location of electrons in atomselectrons in atomsUse the Aufbau diagram to give you the orderUse the Aufbau diagram to give you the orderApply Hund’s rule- keep electrons within a Apply Hund’s rule- keep electrons within a
sublevel unpaired as much as possiblesublevel unpaired as much as possiblePauli Exclusion principle- no more than two Pauli Exclusion principle- no more than two
electrons in an orbital and then only if they electrons in an orbital and then only if they have opposite spinshave opposite spins
Notice that the configuration, while giving Notice that the configuration, while giving less detail, is much easier to doless detail, is much easier to do
KryptonKrypton
The configuration is:The configuration is:
1s1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p66..
Try the filling diagram on your own.Try the filling diagram on your own.
I’ll show a few more and then we’ll look for some I’ll show a few more and then we’ll look for some patterns to make life easier and more efficient.patterns to make life easier and more efficient.
NiobiumNiobium
Element 41Element 41
On the filling diagram we would go from On the filling diagram we would go from 1s, past 4p, then 5s and then 4d (with 1s, past 4p, then 5s and then 4d (with three electrons). This gives a total of 41 three electrons). This gives a total of 41 electronselectrons
1s1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p665s5s224d4d33..
A few moreA few more TinTin IodineIodine BariumBarium
PlatinumPlatinum
RadonRadon
UraniumUranium
1s1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p665s5s224d4d10105p5p22
1s1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p665s5s224d4d10105p5p55
1s1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p665s5s224d4d10105p5p66
6s6s22
1s1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p665s5s224d4d10105p5p6 6
6s6s224f4f14145d5d88
1s1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p665s5s224d4d10105p5p6 6
6s6s224f4f14145d5d10106p6p66
1s1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p665s5s224d4d10105p5p6 6
6s6s224f4f14145d5d10106p6p667s7s224f4f44
Now for some hintsNow for some hints
One way to check your answer- add up all One way to check your answer- add up all of the superscripts (which tell the number of the superscripts (which tell the number of electrons) and see if they agree with the of electrons) and see if they agree with the number of electrons that atom hasnumber of electrons that atom has
This works but is not very convenient for This works but is not very convenient for atoms like uraniumatoms like uranium
Periodic Table GeographyPeriodic Table Geography
The two columns headed 1 and 2 (IA and The two columns headed 1 and 2 (IA and IIA) are often called the s-blockIIA) are often called the s-block
This is because all of the configurations for This is because all of the configurations for those atoms end those atoms end nnss11 and and nnss22 (n stands for (n stands for the period or row number on the table and the period or row number on the table and represents the highest energy level used represents the highest energy level used by that atom)by that atom)
Other “blocks”Other “blocks” The 6 columns on the rights (13-18 or IIIA-VIIIA) The 6 columns on the rights (13-18 or IIIA-VIIIA)
are called the p block. The ending (very last entry) are called the p block. The ending (very last entry) of the configuration for any atom is given by npof the configuration for any atom is given by np11 through npthrough np66. (Helium is an exception- why?). (Helium is an exception- why?)
Notice how there are 6 columns and the p orbitals Notice how there are 6 columns and the p orbitals can hold up to 6 electrons!?can hold up to 6 electrons!?
The transition metals (groups 3-12) are called the The transition metals (groups 3-12) are called the d-block elements are their configurations end d-block elements are their configurations end nsns22(n-1)d(n-1)d11 to ns to ns22(n-1)d(n-1)d1010..
Notice it is n-1. The fourth row on the table uses Notice it is n-1. The fourth row on the table uses 3d orbitals3d orbitals
The two rows at the bottom are f-block elements – The two rows at the bottom are f-block elements – we’ll go over them in more detail in class.we’ll go over them in more detail in class.
How can this help? How can this help? (I hear you ask)(I hear you ask)
Let’s say you are doing the configuration for Let’s say you are doing the configuration for bismuth and you don’t want to add up all the bismuth and you don’t want to add up all the superscripts to see when you reach 83 superscripts to see when you reach 83 electrons.electrons.
Find Bi and notice it is in the p-block.Find Bi and notice it is in the p-block. It is in the 3It is in the 3rdrd column on the p-block so it must column on the p-block so it must
end pend p33.. It is in the 6It is in the 6thth row or period on the table so it row or period on the table so it
ends 6pends 6p33.. Just build up to 6pJust build up to 6p33 and you’ll have it. and you’ll have it.
Determine the endingDetermine the ending
CopperCopper GermaniumGermanium Helium (be careful)Helium (be careful) BromineBromine FranciumFrancium Element 118 (figure Element 118 (figure
out where it would be)out where it would be)
3d3d99
4p4p22
1s1s22 (only has 2 electrons) (only has 2 electrons) 4p4p55
7s7s11
7p7p66
That just gives the endingThat just gives the ending
You still could be expected to do the entire You still could be expected to do the entire configuration and/or the filling diagramconfiguration and/or the filling diagram
But knowing the last part of the But knowing the last part of the configuration can be a big help.configuration can be a big help.
If Cd ends 4dIf Cd ends 4d1010, then Hg must end 5d, then Hg must end 5d1010.. If Ba ends 6sIf Ba ends 6s22, the Ra ends 7s, the Ra ends 7s22..
ExceptionsExceptions
There are a few (okay, actually many) There are a few (okay, actually many) exceptions but all of then can be explained exceptions but all of then can be explained by the following guideline:by the following guideline:
Atoms may “shuffle” an electron or two so Atoms may “shuffle” an electron or two so that the d and f sublevels are either that the d and f sublevels are either completely or filled or half-filled. This completely or filled or half-filled. This means that exceptions tend to revolve means that exceptions tend to revolve around daround d55 and d and d1010 and f and f77 and f and f1414..
Exceptions almost never apply for s and p Exceptions almost never apply for s and p endings.endings.
CopperCopper
Copper should have a configuration ofCopper should have a configuration of1s1s222s2s222p2p663s3s223p3p664s4s223d3d99..But I can also “bump” an electron from 4s But I can also “bump” an electron from 4s
to 3d, which fills the d sublevel. to 3d, which fills the d sublevel. 1s1s222s2s222p2p663s3s223p3p664s4s113d3d1010..This exception can and does happen and This exception can and does happen and
it accounts for why copper ions can be it accounts for why copper ions can be either +1 or +2.either +1 or +2.
VisuallyVisually
3d
4s
3d
4s
We will go over a few more exceptions in class- you should be able to explain an exceptionif I tell you about it. Otherwise assume the filling orderworks “perfectly.”
Valence Electrons & Dot FormulasValence Electrons & Dot Formulas
Definition of valence electrons-Definition of valence electrons-Electrons in the highest occupied energy level Electrons in the highest occupied energy level
of an atomof an atomRemember that in the notation 4pRemember that in the notation 4p33, the 4 , the 4
represents the energy levelrepresents the energy levelOnly s and p orbital electrons are valence Only s and p orbital electrons are valence
electrons (make sure you understand why)electrons (make sure you understand why)Maximum number = 8 (2 in the 2 and 6 in the Maximum number = 8 (2 in the 2 and 6 in the
p)p)
ExamplesExamples
Hydrogen Hydrogen 1s1s11
Lithium 1sLithium 1s222s2s11
Sodium 1sSodium 1s222s2s222p2p663s3s11
Potassium 1sPotassium 1s222s2s222p2p663s3s223p3p664s4s11
Rubidium 1sRubidium 1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p665s5s11
See a pattern?See a pattern?Let’s look at examples from other parts of the Let’s look at examples from other parts of the
periodic table before we summarize thisperiodic table before we summarize this
Some p block examplesSome p block examples Boron 1sBoron 1s222s2s222p2p11
Aluminum 1sAluminum 1s222s2s222p2p663s3s223p3p11
Gallium 1sGallium 1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p11
Indium 1sIndium 1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p665s5s224d4d10105p5p11
The valance electrons in this group (family) are The valance electrons in this group (family) are equal to 3 ( 2 from the s sublevel and 1 from the p equal to 3 ( 2 from the s sublevel and 1 from the p sublevel). Notice how they are near the end of the sublevel). Notice how they are near the end of the configuration but don’t have to be the last entry configuration but don’t have to be the last entry only.only.
Column headed IA had 1 valence electron eachColumn headed IA had 1 valence electron each Column headed IIIA has 3 valence electrons eachColumn headed IIIA has 3 valence electrons each Coincidence?Coincidence?
A few more p block examplesA few more p block examples
Arsenic 1sArsenic 1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p33
This atom, in group VA has 5 valence This atom, in group VA has 5 valence electrons (as do N, P, Sb and Bi)electrons (as do N, P, Sb and Bi)
Fluorine: 1sFluorine: 1s222s2s222p2p55
Chlorine: 1sChlorine: 1s222s2s222p2p663s3s223p3p55
Bromine: 1sBromine: 1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p55
Iodine: 1sIodine: 1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p665s5s224d4d10105p5p55
Transition MetalsTransition Metals
For the most part, we write transition For the most part, we write transition metals as if they have two valence metals as if they have two valence electrons- there are exceptions as electrons- there are exceptions as electrons may be “moved around” to give electrons may be “moved around” to give some filled and half-filled d orbitals but this some filled and half-filled d orbitals but this is a good place to start.is a good place to start.
A few examplesA few examples
Transition MetalsTransition Metals
Titanium 1sTitanium 1s222s2s222p2p663s3s223p3p664s4s223d3d44
Iron 1sIron 1s222s2s222p2p663s3s223p3p664s4s223d3d66
Mercury1sMercury1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p665s5s224d4d10105p5p6 6
6s6s224f4f14145d5d1010
Cadmium 1sCadmium 1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p665s5s224d4d1010
Gold Gold 1s1s222s2s222p2p663s3s223p3p664s4s223d3d10104p4p665s5s224d4d10105p5p666s6s224f4f14145d5d99
Valence ElectronsValence Electrons
Only s and p orbital electrons can be Only s and p orbital electrons can be valence electrons- never d electronsvalence electrons- never d electrons
How we draw them is shown next:How we draw them is shown next:
Dot FormulasDot Formulas
So about those colored flames…So about those colored flames…
First a little background on First a little background on light, the electromagnetic light, the electromagnetic spectrum, and energy and spectrum, and energy and then we can see how those then we can see how those flames got their colors and flames got their colors and how fireworks work.how fireworks work.
Waves and Basics of WavesWaves and Basics of Waves
Light is a part of the electromagnetic Light is a part of the electromagnetic spectrum, a range of energies that travel spectrum, a range of energies that travel as transverse wavesas transverse waves
We can see some of these energiesWe can see some of these energiesMost we can’tMost we can’tJust like there are sounds too high or low Just like there are sounds too high or low
for us to hear, there are light energies that for us to hear, there are light energies that are too high or low for our eyes to detectare too high or low for our eyes to detect
Electromagnetic SpectrumElectromagnetic Spectrum
WavesWaves
Wave basicsWave basics
Wavelength the distance between crests Wavelength the distance between crests as a wave passes a point (unit = m or cm as a wave passes a point (unit = m or cm or some other length unit)or some other length unit)
Frequency- the number of wave crests Frequency- the number of wave crests (peaks) that pass a point every second (peaks) that pass a point every second (unit = 1/sec of Hertz, Hz) often sec(unit = 1/sec of Hertz, Hz) often sec-1-1
Energy depends on the frequencyEnergy depends on the frequencyWave speed = wavelength x frequencyWave speed = wavelength x frequencym/s = m x 1/secm/s = m x 1/sec
How they relate to each otherHow they relate to each otherWavelength and frequency are inversely Wavelength and frequency are inversely
related to each other (one goes up, the related to each other (one goes up, the other goes down)other goes down)
Frequency and energy are directly related Frequency and energy are directly related to each other (one goes up, the other goes to each other (one goes up, the other goes up)up)
Wavelength and energy are inversely Wavelength and energy are inversely related to each other (one goes up, the related to each other (one goes up, the other goes down)other goes down)
VisuallyVisually
SoSo
Gamma rays have very high frequencies, very Gamma rays have very high frequencies, very small (short) wavelengths and very high small (short) wavelengths and very high energiesenergies
Radio waves have long wavelengths, but low Radio waves have long wavelengths, but low frequencies and energiesfrequencies and energies
Red light has a wavelength about double that of Red light has a wavelength about double that of violet light, so it has half the energyviolet light, so it has half the energy
UV light has more energy than IR light, so we UV light has more energy than IR light, so we don’t have to block the IR light from the sundon’t have to block the IR light from the sun
And And
Gamma rays and x-rays are high energy Gamma rays and x-rays are high energy forms of the forms of the EM spectrumEM spectrum, with high , with high frequencies and short wavelengthsfrequencies and short wavelengths
Radio and TV waves have long Radio and TV waves have long wavelengths and low energies and wavelengths and low energies and frequenciesfrequencies
A few calculationsA few calculations
The speed of light is abbreviated c and = 3.00 x The speed of light is abbreviated c and = 3.00 x 101088 m/s (it varies slightly in air or a vacuum but m/s (it varies slightly in air or a vacuum but not much)not much)
A microwave has a frequency of .12m and A microwave has a frequency of .12m and travels at the speed of light (since it is part of travels at the speed of light (since it is part of the electromagnetic spectrum)the electromagnetic spectrum)
Speed = wavelength x frequencySpeed = wavelength x frequency c = c = λλ νν (in symbols, lambda, nu)(in symbols, lambda, nu)
3 x103 x1088 m/s = (.12 m) (freq) freq = 2.5 x 10 m/s = (.12 m) (freq) freq = 2.5 x 1099 Hz Hz
Find the wavelength …Find the wavelength …
Remember that all parts of the Remember that all parts of the electromagnetic spectrum travel at the electromagnetic spectrum travel at the speed of light.speed of light.
What is the wavelength of a gamma ray What is the wavelength of a gamma ray with a frequency of 6 x 10with a frequency of 6 x 102121Hz?Hz?
c = wavelength x frequencyc = wavelength x frequency3 x 103 x 1088 m/s = (wavelength)(6 x 10 m/s = (wavelength)(6 x 102121secsec-1-1))Wavelength = 5 x 10Wavelength = 5 x 10-14-14 m m
Those FlamesThose Flames
Electrons in atoms “prefer” to be in the Electrons in atoms “prefer” to be in the lowest possible energy levels and lowest possible energy levels and sublevels- this is called the “sublevels- this is called the “ground stateground state””
If energy is added to an atom (by heat or If energy is added to an atom (by heat or electricity or high energy light (UV-rays or electricity or high energy light (UV-rays or x-rays perhaps) then on ore more x-rays perhaps) then on ore more electrons may get “bumped up” to a higher electrons may get “bumped up” to a higher energy level. This is called the “energy level. This is called the “excited excited statestate.”.”
And then…And then…
But given any chance, the electrons will But given any chance, the electrons will return to the ground statereturn to the ground state
When they do this, they must give back When they do this, they must give back the energy that originally excited them the energy that originally excited them (conservation and the like)(conservation and the like)
But they can give that energy back as EM But they can give that energy back as EM radiation and if the energy of the light radiation and if the energy of the light emitted is in the visible range, we’ll seeemitted is in the visible range, we’ll see
If the energy is not in the visible range we will If the energy is not in the visible range we will not notice it (but it is still there and might be not notice it (but it is still there and might be detected with the right kind of instruments).detected with the right kind of instruments).
Photon: a “particle” or unit of light with energy proportional to thefrequency (and inversely related to itswavelength).
Photoelectric EffectPhotoelectric Effect This is what Einstein won the Nobel prize for This is what Einstein won the Nobel prize for
(not relativity).(not relativity). The photoelectric effect- when light shines on a The photoelectric effect- when light shines on a
metal electrons are ejected (not just raised to a metal electrons are ejected (not just raised to a higher E level, but ejected from the atom)higher E level, but ejected from the atom)
If the light shining on the metal has too low a If the light shining on the metal has too low a frequency, no electrons are ejectedfrequency, no electrons are ejected
Once the minimum frequency (energy) is Once the minimum frequency (energy) is reached no more electrons are ejected, the ones reached no more electrons are ejected, the ones that are ejected move faster.that are ejected move faster.
Brighter light gives more electrons but at the Brighter light gives more electrons but at the same speedsame speed
Like thisLike this
AndAnd
Wrapping it upWrapping it up
You need to be able to:You need to be able to:Do configurations and filling diagrams for any Do configurations and filling diagrams for any
atom (applying Pauli’s & Hund’s rules and the atom (applying Pauli’s & Hund’s rules and the Aufbau Principle)Aufbau Principle)
Relate the ending to the location on the Relate the ending to the location on the periodic tableperiodic table
Determine valence electrons and dot formulas Determine valence electrons and dot formulas for any atomfor any atom
And And
Describe the contributions of anyone Describe the contributions of anyone mentioned in this unitmentioned in this unit
Know key terms of quantum mechanicsKnow key terms of quantum mechanicsDescribe the waves and the EM Describe the waves and the EM
spectrum, know relationships between spectrum, know relationships between speed, energy, frequency and wavelengthspeed, energy, frequency and wavelength
Explain flame tests and atomic spectraExplain flame tests and atomic spectra
So thereSo there
``Anyone who is not shocked by quantum ``Anyone who is not shocked by quantum theory has not understood a single word.theory has not understood a single word.
Niels BohrNiels Bohr
Very interesting theory - it makes no sense Very interesting theory - it makes no sense at all.at all.
Groucho MarxGroucho Marx
