Download Atomic Theory Notes Packet

Name_______________________________
Chemistry
Atomic Structure
Essential Question: How was the structure of the atom determined?
Vocabulary: bright-line spectrum
electron configuration
excited state
ground state
orbital
wave-mechanical model
Part 3: Wave-Mechanical Model of the Atom
Key Question: How does the wave mechanical model explain the location of electrons?
1. Dalton’s Atomic Theory (1803):
1. ______________________________________________________________________________
2. ______________________________________________________________________________
3. ______________________________________________________________________________
4. ______________________________________________________________________________
2. Modifications to Dalton’s Theory:
JJ Thomson (1897);___________ _______________ model based on his discovery of the electron
Ernest Rutherford (1911): 1. Atom is mostly __________ __________
2. At center of atom is a dense positively charged __________________
3. Niels Bohr and other physicists studied light given off by elements with a ____________________
Why were they studying light? They could apply principles about the nature of light to the nature of
subatomic particles.
What is light?
1. Newton (1600’s): light travels through space as a ___________________
2. Maxwell (1864):
light travels through space as a beam of ________________
4. Electromagnetic Spectrum: (wavelengths in meters)
10-12
10-10
10-8
4 to 7 x10-7
Gamma
X rays
UV
Visible light
10-4
IR
10-2
Micro
Wavelength increases
Frequency decreases
Energy decreases
Speed is constant = 3.00 X 108 m/sec
1
102
Radio waves
FM short
AM
104
5. Properties of Electromagnetic Waves:
Wavelength ( ): distance between two ____________ in a wave
Frequency: ____________ of waves that pass a given point per second
Speed: measured in __________ per second (3.00 x 108 m/s)
6. Bohr: From his observations about light given off by elements
Knew that the color of light emitted by a star or element indicated how much ____________
was being released.
Thought that as an atom gained energy from heat, electricity, etc., that it was the ______________
that gained the energy.
Electrons normally in the ____________ ____________, close to the nucleus
Electrons become ____________ when energy is added and they move away from the nucleus
Excited state is ____________: electrons return to the ground state releasing energy as
____________, ____________, ____________
Bright-line ____________ shows energy released from the electrons as they return to the ground
state
7. Bohr Experiment with the Bright-line Spectrum of Hydrogen
Line Spectra and the Energy Level Diagram
1. In this activity we will investigate the spectrum of hydrogen just as Niels Bohr did in 1913.
Remember that energy may be added to electrons in the form of heat, light, or electricity. As this
energy is added, the electrons are promoted to higher, or excited, energy states. As the electrons
lose this energy, light is emitted. The wavelengths of the light emitted enable us to determine the
energy levels that the electrons occupied.
2. This emitted light may be measured using a spectroscope or diffraction film. From the wavelength,
the ENERGY associated with each color may be determined using the following formula:
EKJ = 119,557
This equation comes from work done by Max Planck and Louis de Broglie who were investigating
the wave-like properties of matter. Energy is measured in kilojoules.
3. Your teacher will place a tube filled with hydrogen gas in a high voltage apparatus. As electricity
flows through the hydrogen, observe the spectrum seen using the diffraction film in the glasses. For
each color observed, record both the color and the wavelength in the table below. The wavelength
Using the equation above, calculate the energy values and record in the table.
Approximate Color
Wavelength
Energy (kilojoules)
4. The energy transitions you have seen occurred when the electrons fell back to the second energy
level. Transitions back to the first level were not seen since they are in the ultraviolet region.
5. Use these values to construct the energy level diagram for hydrogen on the back of this page. For
this diagram you will need to know at what energy the highest energy level is located. This can be
found by using Table S to look up the first ionization energy for hydrogen. This energy is the
amount of energy needed to strip an electron from the atom of hydrogen and therefore corresponds
to the highest possible energy level.
First Ionization energy for hydrogen: __________
6. After completing the plotting of the energies you observed, draw arrows to correspond to the
electrons returning to the second energy level.
1500E
N
E
R
G
Y
(kJ/
mol)
1000-
500-
7. Questions to answer:
________________ a. Which color of light contains the greatest amount of energy?
________________ b. The least amount of energy?
________________ c. To which energy level did all the excited electrons return to?
________________ d. An electron absorbs a specific amount of energy, called a ___, when it jumps
to a higher energy level.
________________ e. Each color represents a specific amount of energy released by an electron
and is called a___.
________________ f. Each line on the diagram represents a different ___ level in the hydrogen
atom.
Bohr Model of the Atom
1. Parts of Bohr’s model:
1.) Electrons orbit the nucleus in __________ orbits at fixed distance called __________ __________
2.) Electrons farther from the nucleus contain (more, less) energy
3.) When electrons gain energy, they move from the _________ __________ to higher energy levels
4.) Electrons return to the ground state by releasing energy in specific amounts called ____________
2. Problems with the Bohr Model
1.) It did not account for all the __________ in the spectra of the other elements.
2.) With better instruments, the model did not even work for ___________.
3. Heisenberg Uncertainty Principle (1927): it is not possible to know the exact __________ and
____________ of a subatomic particle.
4. Wave Mechanical or Quantum Model: based on the _________________ of finding an electron in
a given region of space around the nucleus.
Proposed by Erwin Schrodinger and Louis DeBroglie and uses Bohr’s __________ __________
as distances from the nucleus.
1.) Electrons do not move in __________ paths around the nucleus.
2.) Electrons farther from the nucleus have ________ energy.
3.) An ____________ is a region in space with a high probability of finding an electron.
5. Demonstration- Penny Toss!
Wave Mechanical, or Quantum, Model of the Atom
1. Principal Energy Level (Bohr) = Principal Quantum Number, n
I
N
C
R
E
A
S
I
N
G
n=4
n=3
n=2
E
N
E
R
G
Y
n=1
2. Energy Sublevels: found within the Principal Energy Level (account for the extra lines in the spectra
of other elements)
1.) Number of Sublevels = Principal Quantum Number, n
n = 1, _____ sublevel
n = 2, _____ sublevels
n = 3, _____ sublevels
2.) Energy of each sublevel is slightly _______________.
3.) Each electron in a given sublevel has _______________ amount of energy.
4.) Sublevel symbols are s, p, d, f Draw the sublevels in the diagram above.
3. Orbitals: regions with a sublevel where electrons may be found
1.) Each orbital can hold _____ or _____ electrons.
2.) Number of orbitals in each sublevel
s sublevel = _____ orbital
p sublevel = _____ orbitals
d sublevel = _____ orbitals
f sublevel = _____ orbitals
3.) Number of orbitals in a Principal Energy Level = n2. Use
draw the orbitals in an energy level.
on the diagram on the front to
4. Electron Spin: electron rotates on its axis like the ____________
1.) Opposite spins: ____________ and ____________
2.) Pauli Exclusion Principle: only _____ electrons can occupy the same orbital, each with opposite
spin
5. Shapes of Orbitals:
1.) s orbital: ____________ shape; higher Principal Energy Levels has __________ diameter.
See p. 131 in textbook. Diagram below.
2.) p orbital: ____________ shape around the nucleus and each axis. Diagram below.
6. Hund Rule: must place 1 electron in each p orbital before a second electron can go in. Think of the
Birthday Rule!!
7. Fill in orbital structures for the atoms below. Use these three rules:
Aufbau principle: electrons occupy the orbitals of ____________ energy first.
Pauli exclusion principle: an atomic orbital may describe at most _____ electrons.
Hund’s rule: one electron enters each orbital until all orbitals contain one electron with _____ spin
Element Atomic
Number
1s
2s
2p
3s
3p
4s
H
_____
 


 
Li
_____
 


 
B
_____
 


 
C
_____
 


 
O
_____
 


 
F
_____
 


 
Ne
_____
 


 
Na
_____
 


 
Al
_____
 


 
S
_____
 


 
Ar
_____
 


 
K
_____
 


 
Ca
_____
 


 
8. Summary of Wave Mechanical Model
Principal
Quantum
Number
n
Number of
Orbitals
n2
Sublevel
s
p
d
f
Number of
Electrons
2n2
9. Electron Configurations: shorthand method for showing electron location in an atom.
Write the electron configurations for the atoms listed in #7 on the previous page.
H ___________________________________________________________________________
Li ___________________________________________________________________________
B ___________________________________________________________________________
C ___________________________________________________________________________
O ___________________________________________________________________________
F ___________________________________________________________________________
Ne ___________________________________________________________________________
Na ___________________________________________________________________________
Al ___________________________________________________________________________
S ___________________________________________________________________________
Ar ___________________________________________________________________________
K ___________________________________________________________________________
Ca ___________________________________________________________________________
10. Write the electron configuration for an atom of copper.
Cu ___________________________________________________________________________
Look at the Periodic Table. What does it give for copper’s electron configuration? ___________
Orbital Notation Practice and Questions
1. Complete the orbital notation for the elements below.
Atomic
Number 1s
2s
2p
3s
3p
3d
4s
4p
H _____
       
Li _____
       
Ne _____
       
Si _____
       
Fe _____
       
Br _____
       
1st
2nd
3rd
Principal Energy Levels
2. Complete the following table (Note PQL = Principal Quantum Level, n)
Atomic Number
H=___
Li=___
Ne=___
Si=___
Number of Electrons
Number Occupied Orbitals
Number Filled Orbitals
Number of Unpaired Electrons
Number of Electron Pairs
Number of Occupied Sublevels
Number of Filled Sublevels
Number of Occupied PQL’s
Number of Filled PQL’s
PQL of Highest Occupied PQL
Number of Valence Electrons
(outermost energy level)
Number of Kernel Electrons
(non-valence electrons)
Number of Unpaired Valence
Electrons
4th
Fe=___
Br=___
Significance of Wave Mechanical Model
1. Periodic Table Relationships
1.) Period (row) corresponds to the ____________ ____________ Level being filled with electrons
example: For Period 3, which Principal Energy Level is filling?_____
2.) Electron configurations given in block for each element in _______________ corner.
You need to know the filling order!!
3.) Blocks of elements correspond to the sublevel being filled
s block: Groups _____ and _____ filling
p block: Groups _____, _____, _____, _____, _____, _____ filling
d block: Groups _____ through _____ filling (includes the ____________ elements)
f block: _______________ and _______________ Series filling
2. Belated filling: when an ____ sublevel fills before a lower p sublevel.
Example: 4s fills before the _____
3. Valence Electrons: electrons in the _______________ Principal Energy Level for an element
Valence Shell: corresponds to the __________; determines the __________ properties of an atom
Filled Valence Shell: Group _____ elements called the __________ or __________ Gases
8 electrons in valence shell indicates chemical _______________.
Group: elements in the same vertical column with the __________ number of valence electrons
4. Kernel: nucleus and all _______________ electrons.
5. Excited State Configurations: look for electrons not in lowest possible energy levels
Atomic
Ground State
Excited State
Number
oxygen
_____
1s2 2s2 2p4
1s2 2s2 2p3 3s1
2-6
6. Ions: atoms with __________ or _________ electrons
Atomic
Ground State
Number
oxygen
_____
1s2 2s2 2p4
2-6
__________
Ion
1s2 2s2 2p6
__________