Electron Properties and Arrangement
Chapter 5
Objectives:
• Identify properties of electrons.
•
Understand how electrons move in atoms.
•
Distinguish between atoms based on their different
electron arrangements. .
Electron Properties: 3.27.14
Infinite Campus Update:
•
•
Atomic Structure and Nuclear Chem Gallery Walk (5pts.)
Electron Properties and Arrangement Bell Ringer (4pts.)
Objectives:
• Identify properties of electrons.
• Understand how electrons move in an atom.
Bohr’s Model of the Atom
•Electrons travel in fixed, circular paths
around the nucleus.
•Each path has a specific energy requirement.
•These circular paths are called energy
levels.
•Limited number of electrons on each
energy level. (2n2 Rule)
http://micro.magnet.fsu.edu/
Electrons and Light Particles
Electron Properties:
• Very tiny particles
• Extremely small masses
• Move at very high speeds (3.0x108 m/s)
• Electron movement is identified by the
absorption and emission of light particles by
electrons.
Current Atomic Model
Electrons do not travel in fixed paths around
the nucleus
*Electrons constantly move to different
energy levels in the electron cloud.
*Direction of e- movement is
dependent upon energy absorbed or
released.
Erwin Schrodinger
Electron Movement
1.
2.
3.
Atoms Interaction with Light Particles
Light Particles
Atom
Electrons absorb light particles
•Electrons absorb specific light particles.
•Electrons that absorb photons can move to higher
energy levels.
Electromagnetic Radiation Spectrum
•Electromagnetic Spectrum : Divides light particles into
regions based on their wave-like properties.
a. Relationship b/w wavelength and frequency?
b. Relationship b/w wavelength and energy emission?
c. Relationship b/w frequency and energy emission?
Wave-Like Properties: Wavelength
• Wavelength: length of wave from two neighboring crest.
• Amplitude: height of wave from origin to crest.
Wave-Like Properties: Frequency
Frequency (Hz) : how many waves pass a certain point per
second. Units: Hertz (Hz.)= (waves/second)
Wave-Like Properties: Energy
• Temperature : Represents amount of energy emitted from
light particles.
• Photons: Light particles classified by energy emitted.
*Electron movement dependent upon type of photons
absorbed or released.
Flame Test Lab
Purpose:
• Heat matter (atoms) so that we can observe the
emission of photons from electrons.
Electron Movement
1.
2.
3.
Electron Properties: 3.28.14
Infinite Campus Update:
•
•
Atomic Structure and Nuclear Chem Gallery Walk (5pts.)
Electron Properties and Arrangement Bell Ringer (4pts.)
Objectives:
• Identify properties of electrons.
• Understand how electrons move in an atom.
Flame Test Lab
Conclusion:
What properties of electrons were observed from this
lab?
Post-Lab Questions:
Color’s Wavelength
•Each color has its own unique wavelength.
Electromagnetic Spectrum Applications
•“Electromagnetic Spectrum Song” by Emerson and Wong Yann
Flame Test Lab
Post-Lab Questions:
1. What direction were the electrons moving
when the flame turned colors? Explain.
2. Was the flame test a helpful method in
identifying the unknown solutions? Explain
your answer.
3. Which solution emitted the longest
wavelength of light? Shortest wavelength of
light?
4. What is another example you have observed
of chemicals producing beautiful colors
Wave-Like Properties: Frequency
Frequency (Hz) : how many waves pass a certain point per
second. Units: Hertz (Hz.)= (waves/second)
Visible Region of EM Spectrum
loke.as.arizona.edu
Doppler Effect
Doppler Effect
• Provides evidence of galaxy movement, Edwin
Hubble.
• Our universe is expanding and at an increasing rate.
• Validates the Big Bang Theory-how our universe
was created.
Fireworks: Emission of Light
• Example of elements that can give minerals their
unique colors.
barium= pale green
strontium = red
copper = blue-green
sodium= yellow
• These are common metals used in fireworks.
Electron Properties: 4.9.14
Infinite Campus Update:
•
•
Atomic Theory and Nuclear Reaction Exam(44pts.)
Electron Probability Packet (23pts.)
Due:
• “Where Do Elements Come From” packet
Objectives:
•
•
Understand how electrons move in an atom
Predict the arrangement of electrons in an atom at ground
state.
Current Atomic Model
Electrons do not travel in fixed paths around
the nucleus
*Electrons constantly move to different
energy levels in the electron cloud.
*Direction of e- movement is
dependent upon energy absorbed or
released.
*Electrons move around the nucleus in
different shaped paths.
Erwin Schrodinger
Electron Movement
1.
2.
3.
1. Ground state of H Atom (lowest energy level for e-)
2. A photon (light particle) is absorbed by H’s electron.
Electron becomes excited and jumps to higher energy level.
3. E- returns to ground state and emits (releases) the photon.
Emitted photon’s wavelength can be detected by scientists.
(Infrared region at room temp; Visble region at higher temps.)
Emission Spectrums
•Each element has a unique emission spectrum. (flame test lab).
•Scientist can calculate the energy value of each emission band.
Elements in Stars
• A star is a sphere of super hot gases—mostly hydrogen
and helium. How do we know this?
Carbon, Oxygen,
Heavier elements 2 %
Nitrogen, & Calcium
Helium
29%
Hydrogen
69%
• Every chemical element has a unique emission spectrum.
• Emission spectrums help astronomers identify the
composition of stars.
Temperature of Stars
Electron Movement in Energy Levels
•Quantum of energy:
•Specific energy that is absorbed or emitted by
electrons as they move between energy levels. Energy
difference between two energy levels.
•Scientist can calculate energy emitted by electrons.
•Determine what energy levels electrons move
between in an atom.
Locating an Electron
• Is it possible to know the exact location and
velocity of an electron at any instant in time?
• Very difficult to locate an electron because:
- moving extremely fast
-continuously bombarded by light particles
• When locate an electron with a photon from a
microscope, it changes its velocity in unpredictable
ways.
Heisenberg Uncertainty Principle
Before
Photon
After
Photon
changes
wavelength
It is not possible to know the exact position and
speed of an electron at the same time.
The Quantum Mechanical Model
• An atomic model that best explains the probable
arrangement and movement of electrons at any
moment in time.
• Schrodinger provided evidence for this model using
a complex mathematical equation.
• Depends upon 4 quantum numbers.
Erwin Schrodinger
n-Quantum Number
n = energy levels
• 3-D region of space around the nucleus where an
electron can be found.
• Each energy level has a specific energy value.
• E- must absorb or release a specific quantum of
energy to move between energy levels.
• E- do not travel in an orbit (exact path) around the
nucleus.
Atomic orbitals: Probable paths an electron would
take around the nucleus.
Associate energy levels with rows on the
periodic table.
n-Quantum Number
• Limited number of electrons on each energy level.
• 2n2 Rule determines the maximum number of
electrons on each energy level.
l–Quantum Number
l -number :
• Sublevels within an energy level.
• Sublevels identify the shape of the orbitals.
• There are four different sublevels: s, p, d, f
Orbital Shapes
A maximum of 2 electrons can move in each orbital.
Associate orbitals with certain columns on
the periodic table.
Electron Properties: 4.10.14
Due:
• “Where Do Elements Come From” packet
•
Electron Configuration Worksheet
Objectives:
• Understand how electrons move in an atom.
• Predict the electron configuration of an element at ground
state.
Homework:
• Review notes: Quiz over electromagnetic spectrum and
first two quantum numbers.
Bell Ringer: Electron Arrangement
1. What is the name of the atomic model that best
explains electron arrangement?
2. a. What is the n-quantum number?
b. T or F: Electrons move around the nucleus in
an exact path.
c. What is the maximum number of electrons that
can be on the 6th energy level at any time?
3. a. What is the l-quantum number?
b. Illustrate the s, p, d, f atomic orbitals?
c. How many electrons can move in each atomic
orbital at any one time?
Electromagnetic Spectrum Analysis
Orbital Shapes
A maximum of 2 electrons can move in each orbital.
Orbitals and Energy Requirement
• Electron movement defines orbital shapes for each
sublevel.
• Electrons need energy to move in orbital shapes.
Sublevel’s Orbitals
S-orbital
P-orbital
D-orbital
F-orbital
Energy for electron movement
(Rank in increasing amount of energy)
Electron Configuration:
Orbital Shapes
A maximum of 2 electrons can move in each orbital.
Electron Properties: 4.11.14
Objectives:
• Electron Movement Quiz
• Understand how electrons move in an atom.
•
.
Predict the electron configuration of an element at
ground state.
Electron Configuration
• Electron Configuration Rules:
• Aufbau Principle: Electrons will move in an orbital
of lower energy first. (Electrons are lazy!)
• Pauli Exclusion Principle: Only two electrons can
move in an orbital at the same time.
• Hund’s Rule: When electrons can move in orbitals
of the same energy, they will prefer to be alone
before pairing up. (Electrons are selfish!)
Electron Configuration:
m- Quantum Number
m –number:
• Orientations for each atomic orbital.
• Orbital orientations: The different ways an
electron can make an orbital in 3-D space.
S-Orbital Orientation
• Maximum # of s-orbital electrons on an energy level?
• How many s-orbitals are possible on an energy level?
P-orbital Orientations
• Maximum # of p-orbital electrons on an energy level?
• How many p-orbitals are possible on an energy level?
D-orbital Orientations
• Maximum # of d-orbital electrons on an energy level?
• How many d-orbitals are possible on an energy level?
F-orbital Orientations
•Maximum # of f-orbital electrons on an energy level?
•How many f-orbitals are possible on an energy level?
Orbital Orientations
Electron Configuration Orbital Notation
H:
C:
Zn:
S-Quantum Numbers
S-number :
• The direction an electron spins on its axis in an
orbital.
• If paired, the electrons will spin in opposite
directions.
Electron Configuration Quiz
1. Identify and define the four quantum numbers.
2. How many sublevels (types of orbitals) exist on the third
energy level?
3. a. Determine the electron configuration of a neutral Br
atom and include the orbital notations.
b. How many unpaired electrons does Br have?
c. How many valence electrons does Br have?