electrons resources ted videos
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Electrons resources
• Ted videos
• http://ed.ted.com/featured/YlZZblvz
Agenda:
• Warm-up: Identify 3 facts about electrons
• Where are the electrons?
• Electrons & Electromagnetic Radiation
• Bohr’s Theory
• Return Test: Mastery assessment
See Assignment PageMastery Test on
Electrons
Arrangement in the Atom
Where are the electrons?
• Electrons are traveling at 6 x 10⁶m/sec around the nucleus
• Perspective of the speed: How long would it take a space
vehicle to travel to the moon at the electron’s speed?
Fastest travel to the moon 8 hours, 35 minutesPluto mission fly-by
Distance from Earth to Moon:383,401 km
Electrons:
• Earth to moon distance: 383,401 km– Convert to meters
– Calculate the time to travel to the moon at the speed of an electron (6 x 10⁶ m/sec):
Distance = Time x Speed
Electrons & Electromagnetic Radiation
• By studying the light emitted when heating up a chemical sample, scientists better understood the electron:– Its position in the atom;– Its energy; & – Its role (bonding = forming compounds)
• Scientists used the electromagnetic radiation to study electrons
Electromagnetic Radiation
• Form of energy that has a wave-like properties
• Characterized by – Wavelength– Frequency– Energy
Electromagnetic spectrum• See video clips: 1. NASA – saved
– 2. www.teachersdomain.org/resource/phy03.sci.phys.energy.emspectrum/
• Visible light
• Higher energy than visible light
• Lower energy than visible light
Electrons will give off electromagnetic radiation
-When “energized” by heat, electricity, light or chemical
reactions.
How and why does this happen?
Energy exists in photons
• A photon has a specific amount (or packet) of energy
• Also use the word “quantum of energy”
• Photons with different energy will have specific wavelengths related to the energy
Bohr’s discovery and model: saved video from Discovery EducationStarts with historical perspective
Energy is related to the Electron’s orbits
• When an atom is:
• The electron will:– Start at the – Jump to – Number of jumps is related to
• Key researchers: Bohr, Plank, Einstein
Schrodinger
Bohr’s Model of the Atom
• Electrons orbit the nucleus at:
• Electrons can be excited by:
• When excited, an electron will absorb only a certain amount of energy, (
Bohr’s model
• When excited, the electron
– Called the _________ state
• The electron does not stay in the excited state but falls back toward the nucleus and releases
Bohr’s model
Bohr’s model
• Ground vs. excited state
• Number of electrons that exist at specific energy levels
• Bohr’s model works for hydrogen but not for the complex atoms
Emission Spectrum Lab
Purpose: To relate the unique emission spectra lines of an element to the
energy levels of the atom.
Essential Question: What are the emission spectra for specific elements?
This is?
How do neon lights produce the glowing colors?
FACTS:
• Neon is a colorless, inert (non-reactive, non-flammable) gas
• Neon lights are tubes filled with neon gas.
Neon atoms
• Normal conditions– Electrons are at the ground state– No light (energy) is emitted
• Electricity passing through the tube– Atoms absorb energy– Electrons become excited and unstable– Electrons are pulled back toward the nucleus– Electromagnetic radiation is emitted
Elements and their electromagnetic radiation
• Emissions spectrum
• Unique for each element
• Electrons are excited by electricity
• When they are pulled back by the ____________, they give off __________
Emission Spectrum
• White light– Write the order of the colors
Hydrogen: Nitrogen:Mercury:Neon:Other:
Emission Line Spectra
Emissions Spectra - Simulation
• http://phet.colorado.edu/en/simulation/discharge-lamps
Produce light by bombarding atoms with electrons. See how the characteristic spectra of different elements are produced, and configure your own element's energy states to produce light of different colors.
Emission Spectra
• Unique for each element
• Used to identify elements as part of unknown compounds
Hubble Space Telescope
Bohr Model Animationsfor Elements 1-11
• http://web.visionlearning.com/custom/chemistry/animations/CHE1.3-an-atoms.shtml
• http://web.visionlearning.com/custom/chemistry/animations/CHE1.3-an-atoms.shtml
Electrons in models of atoms
How did scientists figure out the structure of atoms without looking at them? Try out different models by shooting light at the atom. Check how the prediction of the model matches the experimental results.
Exploratory Lab
http://phet.colorado.edu/en/simulation/hydrogen-atom
Quantum Model
• Video – www.teachersdomain.org
Video electron arrangement
• Video – (low volume)
• http://ed.ted.com/featured/YlZZblvz
Probable location of the electron
The electron arrangement represents where an electron can be found 90% of the time.
Methods for Writing Electron Arrangements
• Orbital notation
• Electron configuration
• Noble gas notation
How are you going to remember the names for each method of writing the electron arrangement?
Where are the electrons?
Electron placement analogyAspen Hotel
Hotel Analogy – cont
Hotel Analogy – cont
Rules for Electron Arrangement
• Aufbau:*
• Pauli’s exclusion principle:
• Hund’s rule:
* Check the diagram for the order of increasing energy level
Electron Arrangement Diagram
• n= principal energy level
• Sublevels – s, p, d, f
• Orbitals – Each orbital holds 2 electrons with opposite
spins, shown by arrows:
Incr
easi
ng E
nerg
y
Nucleus
Energy Diagram
n = principal energy level
Sublevels:
Orbitals
Electrons & spin
Incr
easi
ng E
nerg
y
Nucleus
Energy Diagram
n = principal energy level
Sublevels:
Orbitals
Electrons & spin
Examples: Sulfur & Iron
Incr
easi
ng E
nerg
y
Nucleus
Energy Diagram
n = principal energy level
Sublevels:
Orbitals
Electrons & spin
Students:
Phosphorus
Calcium
Krypton
Incr
easi
ng E
nerg
y
Nucleus
Energy Diagram
n = principal energy level
Sublevels:
Orbitals
Electrons & spin
Incr
easi
ng E
nerg
y
Nucleus
Energy Diagram
n = principal energy level
Sublevels:
Orbitals
Electrons & spin
Orbital Notation
• The orbital is indicated by a line____ wioth the name written below.
• Arrows represent the electrons.• Examples
Ne: ___ ___ ___ ___ ___
1s 2s 2p 2p 2p
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
Note: You must write both the lines and the orbital designations under the lines
1s
1s
1s 2s
1s 2s
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p 3s
Element Atomic # Orbital diagram Electron Configuration
H
He
Li
Be
B
C
N
O
F
Ne
Na
Practice• Element Atomic #
Z• H
• He
• Li
• Be
• B
• Orbital Notation___1s___ 1s ___ ___ 1s 2s___ ___1s 2s___ ___ ___ ___ ___1s 2s 2p 2p 2p
Practice
• C
• N
• O
• F
• Ne
___ ___ ___ ___ ___
1s 2s 2p 2p 2p
___ ___ ___ ___ ___
1s 2s 2p 2p 2p
___ ___ ___ ___ ___
1s 2s 2p 2p 2p
___ ___ ___ ___ ___
1s 2s 2p 2p 2p
___ ___ ___ ___ ___
1s 2s 2p 2p 2p
Electron Configuration
• Principal energy level + sublevel
• Use superscripts to show number of electrons in each sublevel
1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
Electron Configuration: Sublevel diagram
• Determining order: Aufbau rules
n=1
n=2
n=3
n=4
n=5
• see figure 5-19 on p.138
Know how to make this chart!
1s
1s
1s 2s
1s 2s
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p
1s 2s 2p 3s
Element Atomic # Orbital diagram Electron Configuration
H
He
Li
Be
B
C
N
O
F
Ne
Na
Check your electron configuration answers using the Periodic Table
Periods
S, P, D, F Blocks
18
Valence Electrons
• Electrons in the outermost (highest) principal energy level– Important– Participate in bonds to make compounds– 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
1s² 2s² 2p⁶ 3s² 3p⁴ 1s² 2s² 2p⁶ 3s¹1s² 2s²1s¹
Electron Configuration
Write
• Potassium
• Aluminum
• Chlorine
Circle the valence electrons.
Electron Dot Notation
• Represents valence electrons
K Al Cl
Maximum number = 8
Octet rule: atoms will lose, gain or share electrons to have 8 valence electrons & become stable
Introducing Noble Gas Notation
Analyze the following examples and propose the rules for writing Noble Gas Notation.
• chlorine [Ne] 3s²3p⁵• iron [Ar] 4s²3d⁶• zinc [Ar] 4s²3d¹⁰• barium [Xe] 6s²
Noble Gas Notation
• Short cut method for electron arrangement• Use the noble gas in the period above the
element
• Example:Na 1s² 2s² 2p⁶ 3s¹- Use Neon - Represent neon’s configuration 1s² 2s² 2p⁶as [Ne]- Use in Na: [Ne] 3s¹
Noble Gas Notation
Element
1s² 2s² 2p⁶ 3s² 3p⁶
1s² 2s² 2p⁶ 3s² 3p⁴
1s² 2s² 2p⁶ 3s¹ 1s² 2s² 2p⁶
Noble Gas Notation
Element1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
3d¹º4p⁶ 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º4p⁵ 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º4p⁴ 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º 4p¹1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
1s² 2s² 2p⁶ 3s² 3p⁶
Noble Gas Notation
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º 4p⁶ 5s²4d¹⁰ 5p⁵
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º4p⁶ 5s² 4d¹⁰5p⁴
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º4p⁶ 5s² 4d¹⁰5p²
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º4p⁶ 5²1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹º4p⁶
Periodic Table: Order based on Electron
Configuration
Identify element– Write atomic number (Z)– Symbol
• Circle or highlight the valence electrons
• Write the electron dot notation
1 18
2 13 14 15 16 17
3 4 5 6 7 8 9 10 11 12
Write the Electron Dot in the correct location for the element
Electron Configuration
• Aufbau is the Rule.Note: However, sometimes the electron
configurations are written in energy level sequence rather than Aufbau sequence.
• This is mostly used for the “d” sublevel.Aufbau sequenceTi: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d²Energy level sequenceTi: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d² 4s²
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