welcome back! yes, i graded the “qu-ests.” your grades are on the portal. 1.open your notebooks....
TRANSCRIPT
Welcome Back!Yes, I graded the “qu-ests.” Your grades are on the portal.
1.Open your notebooks. Write down:– Monday 11-28-11– “Chapter 5 – Electrons in Atoms”– The main objective of this chapter is to identify
precisely where electrons are located within an atom.– Today’s objective: Describe wave properties of light.
2.Draw an image of Rutherford’s model of an atom. – Specifically note the location of the 3 subatomic
particles.– List ways this model may fall short. 1
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Current Atomic Model: Early 1900’s
Rutherford Model of the atom: used experimentation to established that the atom had a nucleus with an overall positive charge and negative electrons orbiting the centerThis Atomic Model did:•a poor job explaining why negative electrons didn’t attract to the positive nucleus•not really address how the electrons were arranged at all•not account for the different behavior of apparently similar chemicals
3. Read the first page of the hand out.
1. Don’t freak out.
2. Read point #1 again. Seriously, don’t freak out.
3. Highlight:– Any words, phrases or names you think may be important.– Any words or phrases that make absolutely no sense at all.
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Quantum Mechanics Overview
Quantum: (Latin, "how much") refers to discrete units (packets/bundles/particles/chunks) that this theory assigns to certain physical quantities (for example energy) Mechanics: branch of physics that deals with atomic and subatomic systems based upon the discovery that waves could be measured in particle-like small packets of energy called quanta
4. In your notebook, create a 2 column table, as shown. List any & all thoughts that come to mind when you think of “light” and “waves.”
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Light Waves
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Light: Behave like a WaveWhat is a wave?a disturbance that propagates through space, often transferring energy
particle movement is perpendicular to the
direction of energy transport
particle movement is parallel to the direction of
energy transport
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Light: Behave like a WaveClasses of waves:mechanical waves: exist in a medium (travel through stuff)electromagnetic radiation (EMR) waves: can travel through vacuum (without a medium)
NOTE: Both Mechanical Waves and EMR Waves can be Transverse and or Longitudinal
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Light: Wave Properties Describing Wavesfrequency (ν [nu]): number of waves
that pass through a point per second (unit: 1/s or Hertz (Hz)) NOT SPEED!!!wavelength(λ [lambda]): distance between peaks or troughs (unit meter with appropriate prefix)amplitude (A): height of the wave (unit meter with appropriate prefix)
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Light: Wave PropertiesElectromagnetic Radiation (EMR): energy that can travel through empty space in a wavelike fashion at the same speed (c =3.00 x 108 m/s)
Examples of EMR light, microwaves, TV rays, UV-rays etc.
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Light: Wave PropertiesElectromagnetic Radiation (EMR): the relationship between frequency (ν) and wavelength(λ) is inverse and the multiplication equals c (3.00 x 108 m/s).
c= λ ν
With higher frequency comes shorter wavelength and vice versa.
Please do this now:1. Write down in your notebook:
– Today’s Date– The main objective of this chapter is to identify precisely where
electrons are located within an atom.– Today’s objective: To observe the light emitted by different
metals and explain how this light might relate to its atomic number.
2. Write down the 2 equations we have learned in this chapter so far.
3. Write down the 2 constants (including their name, symbol, value & units) that we have learned in this unit so far.
4. Homework: read pp144-145. 1. Copy the two figures (5.8 & 5.9) into your notes. 2. Answer #10 p.145 and #50 p.166
5. Read the handout I just gave you. Highlight anything that sounds familiar from yesterday. THE FOLLOW UP QUESTIONS FOR THIS LAB ARE DUE ON TUESDAY 12-6-11. Answer them on the worksheet. 11
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Light: Wave PropertiesInterference Pattern: look that the "double slit experiment with light" and predict what will happenLight behaves as a wave with a characteristic frequency (ν), wavelength(λ), and amplitude (A).
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Light: Wave Properties
Interference Pattern:
Constructive Destructive the waves add the waves
cancel
Happy Monday! Please complete the following in your notebook.
1. Write down:– Today’s Date– The main objective of this chapter is to identify precisely where
electrons are located within an atom.– Today’s objective: To describe how the Bohr model of an atom
mathematically predicts the observable phenomenon of hydrogen’s emission and absorption spectral lines.
2. The “Double Slit” experiment suggests light is a ________________ because of observable __________________ and ____________________ interference patterns.
3. The _____________________________ effect suggests light is a particle because certain thresholds of light energy, or quantities, can cause electrons to “jump” off metal. Einstein called these quantities, or bundles of light _________________________
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Today’s agenda.1. Complete your do now.
2. Homework review.
3. Discuss and observe emission spectrum.
4. Learn about Bohr’s mathematical model.
5. Calculate the energy and energy change for an electron
moving from one quantum level to another.
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Homework Review• Homework review• pp 144 – 145 (copy images 5.8 & 5.9)
10. (p. 145) A continuous spectrum shows the colors of all the wavelengths or white light – like a rainbow or what you see from a prism. An emission spectrum shows the wavelengths corresponding to a given element.
50. (p. 166) • The wavelength of the orange line is 615 nm.• Its frequency is 4.88 x 1014 Hz
• Ephoton = 3.23 x 10-19 J16
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Light: Behave like a Particle?Max Planck: wanted to see why light of
only certain colors was emitted from excited gases or heated metals (like heated iron only glows orange then red)•He looked at emission spectra examples
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Emission SpectrumCreate a 3 column, 5 row chart in your notebook with the following headings.
Gas Color Emission Spectral Lines
Please do this now.1. Write down today’s objective: Using the Bohr-Rydberg
equation, determine the color of the photons emitted as electrons “fall” from each principle quantum energy level.
2. Write down the Bohr-Rydberg equation.3. Write down Rydberg’s constant.4. What type of spectrum is this?
5. Get a set of colored pencils and a chemistry book from the front corner of the room and open to page 72.:1. Color in the visible light spectrum. Match the colors to their
wavelengths.19
Please write down the following in your notebook.• Today’s Date• The main objective of this chapter is to identify precisely
where electrons are located within an atom.• Today’s objectives:
1. Understand how and why EMR (specifically light) interacts with atoms and determine which of the 4 models of the atom best simulates this.1. Finish computer simulation “Models of the Hydrogen Atom”
2. Finish flame test
2. Mathematically calculate a photon’s Energy, Frequency and Wavelength that is associated with quantum movement of an electron in the Bohr Hydrogen model.1. Review 8 homework calculations
2. Summarize with notes / presentation.
3. Take home quiz EMR Production. 20
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Light: Behave like a Particle?
Particles (or chunks) of light are called photons. Effect of photons on electrons.
Planck found Equantum=hν where E is energy, h is Planck’s Constant (6.626 x 10-34 J.s and J is Joule the SI unit of energy) and ν is frequency
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Light: Behave like a Particle?
Photoelectric Effect: electrons are emitted from the surface of a metal only when light of a specific frequency is shone •Wave model of light predicts that with enough low frequency light energy could build up and emit electrons from the surface of a metal
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Light: Behave like a Particle?
Photoelectric Effect: electrons are emitted from the surface of a metal only when light of a specific frequency is shone •However, this was not the case because all metals seemed to have a threshold frequency below which photoelectric electron ejection did not occur•This led Einstein to expand on Planck’s ideas and state Ephoton=hν where E is energy, h is Planck’s Constant (6.626 x 10-34 J.s and J is Joule the SI unit of energy) and ν is frequency.
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Light: Behave like a Wave or Particle or Both or Neither?
Summary of the Evidence (so far) Light can sometimes be perceived as behaving like a wave:•Interference Patterns
–Aligned light signals constructively interfere (amplify)–Completely unaligned light signals destructively interfere (cancel)
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Light: Behave like a Wave or Particle or Both or Neither?
Light can sometimes be perceived as behaving like a particle:•Quantized emission and absorption spectra
–Only certain colors were emitted from heated gases–Only certain colors were absorbed by cooled gases
•Photoelectric effect–Electrons could only be ejected from the surface of a metal if a threshold of energy is reached
Objectives
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• The main objective of this chapter is to identify precisely where electrons are located within an atom.
• To define the 4 quantum numbers of Schrodinger’s equation and understand what they represent for the location of the electron.
Today you’re going to feel something like this…
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…or this.
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Tomorrow you should be right between this...
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…and this.
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By mid-week, hope for this…
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…or this.
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By the end of the week, you’ll be somewhere between this…
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…and this.
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Welcome to Quantum!
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Current Atomic Model: Early 1900’s
Bohr Model of the atom: agreed that the atom had a positive nucleus but using the recently discovered ideas of Planck & Einstein, stated that electrons orbited the nucleus at certain specific distances and subsequently energy levels (n)This Model did:•a good job explaining why negative electrons didn’t collapse into the positive nucleus•not actually predict the correct spectra for any other atoms besides hydrogen•make the false assumption that electrons orbit the nucleus like planets around the sun
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Quantum Concept
This model did:• a good job starting the quantum mechanical movement•a good explaining why negative electrons didn’t collapse into the positive nucleus (electrons were moving as waves)•a good job explaining why different elements only emitted specific colors of light when excited
De Broglie Model of the atom: agreed with Bohr but stated electrons behave as waves that move around the nucleus as described by the De Broglie Equation λ =h/mv where λ is wavelength, h is Plank’s Constant, m is mass, and v is velocity. specific colors of light when excited
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Heisenberg Uncertainty Principle
Consequence of the Quantum Concept: If electrons can be perceived as waves that are affected by light waves, then:Heisenberg Uncertainty Principle: it is not possible to know both the position and velocity of electrons because light must be shone on electrons to determine their position which will then change their velocity
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Quantum ConceptSchrodinger: agreed with Bohr but considered the Heisenberg Uncertainty Principle to calculate the probability of finding an electron (as a wave/ particle) in a given 3D space This model:•did a good job pinning down where the electron was most of the time•expressed the 3D region (atomic orbital) as the space where there was a 90% probability of finding a given electron at a given energy level (n)•explained electron behavior for all elements
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The Schrodinger Equation
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This evil looking equation spits out 4 numbers.
The Four Quantum Numbers
• n principal quantum number
• l angular momentum
• ml magnetic quantum number
• ms magnetic spin quantum number
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n principal quantum number
• Also known as– shells
• What it does:– Very similar to n in the Bohr hydrogen model.– Determines the energy of an electron – Related to the average distance of the electron from
the nucleus
• Positive, whole number integers starting with 1:– 1, 2, 3, 4…
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l angular momentum• Written as a cursive, lower case “L”• Also known as
– orbital quantum number
– Azmuthal quantum number
– Sublevel
• Each orbital can hold 2 electrons• What it does:
– Describes the motion of an electron around the nucleus.
– Describes a 3D shape
– Ranges from 0 to n-1
• L = 0 s: sphere
• L = 1 p: peanut
• L = 2 d: 4 leaf clover (plus a weird one)
• L = 3 f: gets really funky44
Sublevels
• Nodes…Lobes
ml magnetic quantum number
• Designates the orientation of an orbital in a 3-D space.
• Values – whole numbers– -l to +l
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ms magnetic spin quantum number
• Represents the spin of an electron.
• Electrons pair up in orbitals:– One must have a +1/2 value and the other is
a -1/2 value
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An s orbital (L = 0)
• No nodes so L = 0• Only one way to orient
a sphere in space
• ml = 0
• 2 electrons exist in this orbital– ms = + ½
– ms = - ½
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p orbitals (L = 1)
• 1 node so L = 1• 3 ways to orient a “peanut” in space
• ml = -1, 0, +1
• 2 electrons exist in each orbital. • 3 orbitals 6 electrons total.
– ms = + ½
– ms = - ½
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d orbitals (L = 2) • 2 nodes so L = 2• 5 ways to orient d orbitals in space
ml = -2, -1, 0, +1, +2
• 2 electrons exist in each orbital• 5 orbitals 10 electrons total.
–ms = + ½
–ms = - ½
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f orbitals (L = 3) • 3 nodes so L = 3• 7 ways to orient d orbitals in space
– ml = -3, -2, -1, 0, +1, +2, +3
• 2 electrons exist in each orbital• 7 orbitals 17 electrons total.
– ms = + ½
– ms = - ½
So what?
• Every electron has a unique set of the 4 quantum numbers – its like a secret code or a postal address.– State– City– Street– House number
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Let’s summarize
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n shape subshell label
L(0 n-1)
energy
= n + L
ml ms # of
orbitals# of
electrons
1 s 1s 0 1 0 + 1/2 1 2
2 s 2s 0 2 0 + 1/2 1 2
2 p 2p 1 3 -1, 0, +1 + 1/2 3 6
3 s 3s 0 3 0 + 1/2 1 2
3 p 3p 1 4 -1, 0, +1 + 1/2 3 6
3 d 3d 2 5 -2, -1, 0, +1, +2 + 1/2 5 10
4 s 4s 0 4 0 + 1/2 1 2
4 p 4p 1 5 -1, 0, +1 + 1/2 3 6
4 d 4d 2 6 -2, -1, 0, +1, +2 + 1/2 5 10
4 f 4f 3 7 -3, -2, -1, 0, +1, +2, +3 + 1/2 7 14
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Quantum ConceptSchrodinger’s Atomic Orbitals: calculated that different energy levels (n) had different shapes and sizes (each e- has a room in a house on a street in a town)• n (the principal quantum number) can range 1-7• as n increases the number of possible different shapes (which are called sublevels) increases• each sublevel (s, p, d or f) has a certain number of atomic orbitals (s=1, p=3, d=5, f=7)• each atomic orbital has a capacity of two electrons
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Current Atomic Model: Early 1900’s
Bohr Model of the atom: agreed that the atom had a positive nucleus but using the recently discovered ideas of Planck & Einstein, stated that electrons orbited the nucleus at certain specific distances and subsequently energy levels (n)This Model did:•a good job explaining why negative electrons didn’t collapse into the positive nucleus•not actually predict the correct spectra for any other atoms besides hydrogen•make the false assumption that electrons orbit the nucleus like planets around the sun
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Quantum Concept
This model did:• a good job starting the quantum mechanical movement•a good explaining why negative electrons didn’t collapse into the positive nucleus (electrons were moving as waves)•a good job explaining why different elements only emitted specific colors of light when excited
De Broglie Model of the atom: agreed with Bohr but stated electrons behave as waves that move around the nucleus as described by the De Broglie Equation λ =h/mv where λ is wavelength, h is Plank’s Constant, m is mass, and v is velocity. specific colors of light when excited
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Heisenberg Uncertainty Principle
Consequence of the Quantum Concept: If electrons can be perceived as waves that are affected by light waves, then:Heisenberg Uncertainty Principle: it is not possible to know both the position and velocity of electrons because light must be shone on electrons to determine their position which will then change their velocity
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Quantum ConceptSchrodinger: agreed with Bohr but considered the Heisenberg Uncertainty Principle to calculate the probability of finding an electron (as a wave/ particle) in a given 3D space This model:•did a good job pinning down where the electron was most of the time•expressed the 3D region (atomic orbital) as the space where there was a 90% probability of finding a given electron at a given energy level (n)•explained electron behavior for all elements
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The Schrodinger Equation
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This evil looking equation spits out 4 numbers.
The Four Quantum Numbers
• n principal quantum number
• l angular momentum
• ml magnetic quantum number
• ms magnetic spin quantum number
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n principal quantum number
• Also known as– _________________
• What it does:– Very similar to n in the Bohr hydrogen model.– Determines the ______________ of an electron – Related to the _________________ of the electron
from the nucleus
• Positive, whole number integers starting with 1:– _____________________
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l angular momentum• Written as a cursive, lower case “L”• Also known as
– orbital quantum number
– Azmuthal quantum number
– _______________________
• Each orbital can hold 2 electrons• What it does:
– Describes the ____________ of an electron around the nucleus.
– Describes a _____________________
– Ranges from __________________
• L = 0 s: sphere
• L = 1 p: peanut
• L = 2 d: 4 leaf clover (plus a weird one)
• L = 3 f: gets really funky63
Sublevels
• Nodes…Lobes
ml magnetic quantum number
• Designates the ______________ of an orbital in a 3-D space.
• Values – whole numbers– ___________________
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ms magnetic spin quantum number
• Represents the _________ of an electron.
• Electrons pair up in orbitals:– One must have a _________ value and the
other is a __________ value
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An s orbital (L = 0)
• No nodes so L = 0• Only one way to orient
a sphere in space
• ml = 0
• 2 electrons exist in this orbital– ms = + ½
– ms = - ½
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p orbitals (L = 1)
• 1 node so L = 1• 3 ways to orient a “peanut” in space
• ml = -1, 0, +1
• 2 electrons exist in each orbital. • 3 orbitals 6 electrons total.
– ms = + ½
– ms = - ½
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d orbitals (L = 2) • 2 nodes so L = 2• 5 ways to orient d orbitals in space
ml = -2, -1, 0, +1, +2
• 2 electrons exist in each orbital• 5 orbitals 10 electrons total.
–ms = + ½
–ms = - ½
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f orbitals (L = 3) • 3 nodes so L = 3• 7 ways to orient d orbitals in space
– ml = -3, -2, -1, 0, +1, +2, +3
• 2 electrons exist in each orbital• 7 orbitals 17 electrons total.
– ms = + ½
– ms = - ½
So what?
• Every electron has a unique set of the 4 quantum numbers – its like a secret code or a postal address.– State– City– Street– House number
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n shape subshell label
L(0 n-1)
energy= n + L
ml ms # of
orbitals# of
electrons
1 s
2 s
2 p
3 s
3 p
3 d
4 s
4 p
4 d
4 f
Please write this in your notebook now.
• The main objective of this chapter is to identify precisely where electrons are located within an atom.
• Today’s objective: To connect the 4 quantum numbers to 3-D orbital models.
• Please take out your homework and complete your “do now.”
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Agenda
• Do now
• Nodal planes
• Balloon activity
• Summary chart
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Use your notes from yesterday to fill this out. Today’s date: __________
• According to Schrodinger’s wave function, orbitals represent a 3-D ________ in which we have a ____% probability of finding an electron (as a wave / particle).
• The 4 quantum numbers are:– n represents _______________________________________– L represents _______________________________________
– mL represents ______________________________________
– ms represents ______________________________________
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orbital shape
s
p
d
principle quantum #, energy level, distance from nucleus.
angular momentum, orbital or shape
magnetic quantum #, orientation of the orbital in a 3D space
“spin” of an electron + 1/2
sphere
peanut, unshelled
3d clover
space 90
Nodal Planes
• A nodal plane is an area of zero displacement – where there is no chance of finding an electron.
• In a sphere, there are 0 nodal planes.
• If we wanted to add a nodal plane to a sphere, what shape would we end up with?
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Summary (will be constructed on the board)
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n shape subshell label
L(0 n-1)
energy
= n + L
ml
(-L to + L)
ms # of
orbitals# of
electrons
1 s 1s 0 1 0 + 1/2 1 2
2 s 2s 0 2 0 + 1/2 1 2
2 p 2p 1 3 -1, 0, +1 + 1/2 3 6
3 s 3s 0 3 0 + 1/2 1 2
3 p 3p 1 4 -1, 0, +1 + 1/2 3 6
3 d 3d 2 5 -2, -1, 0, +1, +2 + 1/2 5 10
4 s 4s 0 4 0 + 1/2 1 2
4 p 4p 1 5 -1, 0, +1 + 1/2 3 6
4 d 4d 2 6 -2, -1, 0, +1, +2 + 1/2 5 10
4 f 4f 3 7 -3, -2, -1, 0, +1, +2, +3 + 1/2 7 14
Use your notes from yesterday to fill this out. Today’s date: __________
• According to Schrodinger’s wave function, orbitals represent a 3-D ________ in which we have a ____% probability of finding an electron (as a wave / particle).
• The 4 quantum numbers are:– n represents _______________________________________– L represents _______________________________________
– mL represents ______________________________________
– ms represents ______________________________________
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orbital shape
s
p
d
Please do this now.• Write down today’s objective:
– “To organize electrons in energy diagrams, orbital diagrams and electron configurations based on their 4 quantum numbers.”
• How many orbital exist for each sublevel (s, p, d, f)?
• How many electrons exist in each orbital?
• For every orbital (1s 4f) determine the summative amount of energy it has.
– (Just add n +L on the chart we filled out yesterday.)
• How many electrons do each of the following elements have?– helium– nitrogen– neon
• Take out your homework.79
Every electron has a home. (aka orbital)
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Each home is occupied by 2 electrons. One lives “upstairs” on lives “downstairs.”
Energy Diagram
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• We can fill out a chart called an energy diagram. • First, let’s write out the orbitals from lowest
energy to highest. (i.e. 1s, 2s …)• Pay attention to the number of orbitals each
sublevel has.• Each box represents a home (an orbital) for
electrons.• Electrons fill lower energy levels first.• Consider nitrogen.
Three Rules
1. Aufbau Principle: - electrons are lazy and fill orbitals one at a time to the lowest energy level.
2. Pauli Exclusion Principle:- to live in the same “house”, one must be “upstairs” one “downstairs”
3. Hund’s Rule:- electrons are loners – maximize unpaired electrons.
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After the bell – at 10:39.
1. Be IN the video amphitheater before 10:39.
2. As you walk in, place all of your stuff to the seats all the way to the left of the room.
1. Keep with you your notebook, your notes and a writing utensil.
3. Stand in the bottom of the amphitheater, in a line with your classmates.
1. Line up by how much caffeine you consume on an average day.
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We can collapse this energy diagram into an orbital diagram.
Orbital Diagram
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1s 2s 2p 3s
Carbon has 6 electrons – fill them in just like in the energy diagram.Or, simply write an electron configuration.
1s22s22p2
Today’s work:
• By the end of class, complete the last sheet of your first packet and give it to me.
• For the rest of class – work on your electron configuration packet. Finish it for homework.
• Have a wonderful and safe weekend.
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1s89
2s90
2p91
3s92
3p93
4s94
3d95
4p96
4d97