HONORS CHEMISTRY

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HONORS CHEMISTRY

• September 9, 2013

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Atomic History

• Democritus
• Dalton
• JJ Thomson
• Rutherford
• Chadwick
• Bohr

• Matter is composed of empty space in which atoms
  move
• Elements consist of atoms and compounds are
  collection of atoms
• Plum pudding model Atoms contain negative
  particles called electrons
• Alpha particles, positive charge with a mass
  7500x of electron. Proved the plum pudding model
  was wrong. Nucleus center ( ) and tiny electrons
  moved in space around it.
• Discovered neutrons (slightly more massive than a
  proton).
• Electrons are in circular paths depending on
  their energy levels

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Atomic History

• De Broglie
• Schrodinger
• Millikan
• Moseley

• electrons move in waves rather than straight
  circular paths
• Wave Mechanical Model or Quantum Mechanical
  Model. Furthered De Broglies idea of waves by
  stating that electrons are in clouds but in
  certain energy region
• Oil drop experiment discovered that atoms had
  positive and negative charges and that they equal
  each other
• Helped to arrange atoms in the periodic table.
  Atoms were arranged in increasing atomic number
  using wavelengths and
• x-rays

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Atoms, Isotopes and Ions

• How do atoms of different elements differ?

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The Modern View of Atomic Structure

• What are the particles that make up an atom and
  how do they differ from one another?
• proton mass 1 amu charge 1
• neutron mass 1 amu charge 0
• electron mass 0 amu charge -1
• 1 amu 1.6726 x 10-27 kg

02m14an1
1/1840

• atoms have equal numbers of protons and electrons
  so they are electrically neutral

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Atomic Number

• Atomic number
• Number of protons in an atom
• Identifies the element

12.01115
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Atomic Number

• Use the Periodic Table to complete the following.
  
• 1. What element has the atomic number 18?
• 2. What element has 35 protons?

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How are atoms of one element different from those
of another element?

• They have different numbers of these subatomic
  particles.

Atomic Number
Chemical Symbol
Element Name
1.00797
Average Atomic Mass
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Isotopes

• How do we distinguish between atoms?
• Do all atoms of an element have the same
  composition?
• Heavy Water and Water Ice Cube in water

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Isotopes

• What implication does this have for the masses of
  atoms?
• Average atomic mass
• Isotopes differ only in the number of Neutrons
• Difference is shown by their mass numbers
• Notation superscript for mass number, which is
  the sum of the number of protons and neutrons
• Notation subscript for atomic number, which is
  the number of protons (or electrons)
• 73Li 94Be 115B

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Nuclear Particles

• How many of each particle (protons, neutrons and
  electrons) are in these atoms?
• 7635 Br 7835Br
  8035Br
• 147N 157N
• 188O 178O 168O 158O

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Ions

• When an atom loses or gains electrons and
  acquires a net electrical charge.
• Gain electrons negative ion - anion
• Lose electrons positive ion - cation

Mg2
Mg
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Ions

• Charge of ion of protons - of electrons
• How many protons, neutrons and electrons does
  4120Ca2 have?
• How many protons, neutrons and electrons does
  7835Br - have?

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Think-Pair-Share

• Atomic Structure Worksheet

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Closure

• 1. How many protons, neutron and electrons does
  Mg have?
• 2. How many protons, neutron and electrons
• does 74Be -2 have?

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HONORS CHEMISTRY

• September 10, 2013

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Brain Teaser

• Place homework on your desk
• How many protons, neutrons and electrons does
  3211Na 1 have?
• Who developed the planetary model of the atom
  based on quantum energy levels
• Who discovered that most of the atoms mass is
  located in the nucleus of an atom and the atom is
  mostly empty space
• Who discovered the electrons and developed the
  plum pudding model of the atom

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Agenda

• Brain Teaser
• Grade Homework Atomic Structure Worksheet
• Notes
• Wave and Particle Nature of Light
• Line Spectra
• Quantum Theory
• Bohr Models
• Homework
• Bohrs Model Worksheet/Isotope Worksheet

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Review (Insert)

• Mass of Proton 1.67 x 10-24 grams 1 amu
• Mass of Neutron 1.67 x 10-24 grams 1 amu
• Mass of Electron 9.1 x 10-28 grams (essentially
  zero)

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Unit 3Light and Quantized EnergyElectron
Configuration

• Objective
• Learn how electrons are arranged in an atom and
  how that arrangement plays a role in their
  chemical behavior

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How do we know what makes up an atom?
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The Atom is a Scientific Model

• With the scanning tunneling microscope we can see
  atoms, but we still cannot see their internal
  structure.
• Scientific models are created by experiments, but
  are often modified.
• There may be flaws in the current model.

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What do atoms look like?

• See the electron microscope image of the
  molecular art drawn with gold (Au) atoms.
• See the image of graphite. Are these images
  proof of atoms? How do we see atoms?

nickel
benzene
graphite
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How do we know what makes up atoms?
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Cathode Ray Tubes

• Why does the beam bend?

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Gold Foil Experiment

• Examine the diagram of Rutherfords alpha ray
  experiment. What is the implication of this
  experiment?

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Line Spectra

• Bright Line Spectra
• Lines of color produced by light emitted from
  heating substances and passing them through a
  prism
• Fingerprints of elements
• Researchers can determine values of energy levels
  in atoms
• Used to identify different elements

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Observation of unique line spectra led to Quantum
Theory
Eh?
Fourth
Third
Second
First
Nucleus
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• Demo
• Point Spectroscope towards the fluorescent light
  bulb
• Observe the bright line spectrum of mercury and
  phosphorous

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Where all of this has led to

• Bohr Model did some good things but it is not
  the whole truth.

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Some Questions

• Color arises from electrons shifting from one
  orbital to another of different energy
• Ground state and excited state
• What shift would give rise to emission of light?
  to absorption of light?

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Where all of this has lead to

• Quantum Model

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What is the Quantum Mechanical Model?

• It predicts quantized energy levels for
  electrons, like the Bohr model.

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What is Quantum Theory?

• It does not describe the exact path that
  electrons take around the nucleus of an atom, but
  is concerned with the probability of an electron
  being in a certain place.

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Nucleus
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Orbitals

• Areas where an electron can be found
• Can have up to two electrons
• Fuzzy boundaries ? Electron Cloud

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The Closed Sphere Model

• For convenience
• Shows where the electron is 90 of the time

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The Heisenberg Uncertainty Principle

• You can never know exactly where an electron is
  if you know exactly how fast it is moving.
• You can never know exactly how fast an electron
  is moving if you know exactly where it is.

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Bohr DiagramPractice Worksheet
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THE END
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HONORS CHEMISTRY

• September 12, 2012

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Brain Teaser

• Place Homework on your desk
• Write the complete symbol from the given
  information below
• 20 protons, 22 neutrons, 18 electrons
• 15 protons, 17 neutrons, 18 electrons
• 17 protons, 18 neutrons, 17 electrons
• How many protons, neutrons, and electrons are
  there for each of the following atoms or ions?
• 12 B3
• 80 35 Br

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Agenda

• Brain Teaser
• Grade Homework
• Bright Line-Emission Spectra
• Practice Quiz
• Homework
• Study for Quiz (Friday)

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Grade Homework

• Bohr Diagram Worksheet
• Look for patterns
• Period
• Group
• Label Periodic Table
• Isotopes Worksheet

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Bright Line Emission Spectra Lab Activity

• Objective
• Identify different metals through flame tests and
  using bright line emission spectra

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Background

• Light Electromagnetic radiation
• Frequency of light relates to energy (Diagram)
• Higher Frequency Higher Energy
• Frequency and Color are related
• (Low)Radio, M, IR, Visible, UV, X-Ray, Gamma
  Ray(High)
• Visible Light (Lower) R O Y G B I V (Higher)
• White light has all the colors
• Prism/Diffraction Gratin ? Breaks up colors
• Gaseous element contained in a tube ? energize it
  with electricity ? glow/gives off visible light

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Background

• Electrons absorbing energy excited
• Electrons giving off energy ? Gives off light
• All atoms have all energy levels but they may
  not have e- on them. (Diagram)
• e- jumps to a higher energy level excited state
• e- will give off energy/falls back down ? give
  off visible light (lowest possible energy level
  ground state)
• Energy of photon is proportional to the color
• Some energy are given off as invisible spectrum
  like IR or UV
• Red photon is lower in energy compared to blue
  photon

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Background

• Tube filled with Ne, H, or He (discrete lines) ?
  Atomic Emission Spectra
• e- cannot have any amount of energy but only
  certain amount of energy (no in b/w color)
• Evidence only certain colors are given off.
  e- exist only at certain distances from
  the nucleus
• Every element has a unique emission spectrum
  because it has different electron configuration
• Emission Spectra as a fingerprint of elements
• Applications Astrophysics or Forensics

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Background

• Electrons are only allowed in certain energy
  levels, only have a certain amount of energy, can
  only give off a certain amount of energy
  (quantized energy)
• Different elements have different frequencies and
  they give off a different set of colors

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Line Spectra
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Observation of unique line spectra led to Quantum
Theory
Eh?
Fourth
Third
Second
First
Nucleus
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Element Finger Print
07m07an1
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Spectroscopes

• Practice using the Spectroscopes
• What do you see?
• Where is it coming from?

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LabLine Spectrum Station Rotation
At each Station

• Spectra
• Observe through spectroscope
• Record measurements and notes
• Switch roles to judge precision of observation

• Data Analysis
• Compare spectra to various reference sources
• Identify substance
• Work on study questions

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Lab Rotation

• Identify the emission spectra for 5 gas tubes and
  4 stations for Flame tests
• Flame test Dip the sticks in water and WEAR
  GOGGLES!
• Use colored pencils to mark the reference for
  each station (Gas Tubes)
• Use colored pencils to mark the reference for
  Flame Tests
• Write a qualitative analysis on each emission
  spectrum

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Questions?
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Color Coding the Periodic TableActivity

• Read handout
• Fill out Family Ties (Student Worksheet)
• Homework
• Study for Quiz (Friday)

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Start
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LabLine Spectrum Station Rotation
At each Station

• Pair A
• Spectra
• Observe through spectroscope
• Record measurements and notes
• Switch roles to judge precision of observation

• Pair B
• Data Analysis
• Compare spectra to various reference sources
• Identify substance
• Work on study questions

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Spectroscopes

• What do you see?
• Where is it coming from?

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Line Spectra
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HONORS CHEMISTRY

• September 17, 2012

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Brain Teaser

• Explain why each element can produce its own
  bright line spectrum

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Agenda

• Brain Teaser
• Pre-Test Periodic Trends
• Notes
• Bohrs Model
• Orbital Diagrams and Electron Configuration
• Practice Writing electron configuration
• Homework
• Electron configuration worksheet

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Bohr's Model

• Model ofelectronsin fixedorbits to explain
  quantization Figure 6.14
• Transitionsbetweenorbitsemits orabsorbslight

07m07an1
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Observation of unique line spectra led to Quantum
Theory
Eh?
Fourth
Third
Second
First
Nucleus
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Orbital Diagrams and Electron Configurations

• n Principle quantum number
• Describes the energy level the electron occupies

n 4
n 3
n 2
n 1
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Orbital Energy Levels

• Shape of orbital
• designated by the
• letters
• s, p, d, f, g

Excited states
Ground state
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Shapes of Orbitals

• Shape of orbital designated by the letters
• s, p, d, f, g
• Orbitals have different shapes

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s Orbital shape
The s orbital has a spherical shape centered
around the origin of the three axes in space.
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p orbital shape
There are three dumbbell-shaped p orbitals in
each energy level above n 1, each assigned to
its own axis (x, y and z) in space.
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d orbital shapes
Things get a bit more complicated with the five d
orbitals that are found in the d sublevels
beginning with n 3. To remember the shapes,
think of double dumbells
and a dumbell with a donut!
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Shape of f orbitals
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Combination of electron microscopy and
x-ray diffraction produced image of orbitals
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Sets of Orbitals (Subshells)

• Depending on the type of orbital, we find that
  they occur in sets differing in their orientation
  in space
• s - set of 1
• p - set of 3
• d - set of 5
• f - set of 7

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Sizes of orbitals

• Size depends on the value of n
• Orbitals with the same n are about the same size

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Check for understanding

• What is the principal quantum number for Ar?
• What are the subshells?
• How many sets of electrons are found in each
  subshell?

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Electron Configurations of Some Atoms

• The firstten elements

• 1s1
• 1s2
• 1s2 2s1
• 1s2 2s2
• 1s2 2s2 2p1
• 1s2 2s2 2p2
• 1s2 2s2 2p3
• 1s2 2s2 2p4
• 1s2 2s2 2p5
• 1s2 2s2 2p6

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Shorthand Notation for Orbitals

• Combinations of first two quantum numbers number
  of orbital types equals the shell number (n).
• 1s
• 2s, 2p
• 3s, 3p, 3d
• 4s, 4p, 4d, 4f
• 5s, 5p, 5d, 5f, (5g)
• 6s, 6p, 6d, 6f, (6g, 6h)
• (Stop Period 5)

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HONORS CHEMISTRY

• September 18, 2012

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Brain Teaser

• Place Homework on your desk
• Write the Electron Configuration for the
  following elements
• Si
• Co
• Se

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Agenda

• Brain Teaser
• Grade Worksheet
• Review
• Writing Electron Configuration
• Notes Orbital Diagram
• Homework
• Short Hand Electron Configuration
• Orbital Diagram

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Grade Homework

• Refer to Worksheet (Arrangement of Electrons I)

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Check for understanding (P6)

• What is the principal quantum number for Ar?
• What are the subshells?
• How many sets of electrons are found in each
  subshell?

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Aufbau Principle

• Aufbau Principle start with the nucleus and
  empty orbitals, then build up the electron
  configuration using orbitals of increasing energy

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Electron Configurations

• Electron Spin and Pauli Exclusion Principle
• Only two electrons can occupy a single orbital
  and they must have opposite spins

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Electron Configurations

• Hund's Rule
• When filling a subshell, such as the set of 3 p
  orbitals, place 1 electron in each before pairing
  up electrons in a single orbital

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Electron Configurations

• Arrangement of electrons in the orbitals is
  called the electron configuration of the atom
• The ground state configuration can be predicted,
  using the Aufbau Principle, the Pauli Exclusion
  Principle, and Hunds Rule.

Electron configurations
Filling _ rules.exe
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How do we know what the filling order is?

• What chemistry tool might we rely on?

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Electron Configurations and the Periodic Table

• Valence electron configurations repeat down a
  group

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Ground state electron configurations

• Example Li
• atomic number 3
• nucleus has 3 protons
• neutral atom has 3 electrons
• 2 electrons in 1s orbital, 1 electron in 2s
  orbital

2s
1s
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Different ways to show electron configuration
Box notation
Energy level diagram
?
??
2s
2s
1s
1s
Spectroscopic notation
Li 1s2 2s1
Read this one s twonot one s squared
Write the superscript 1.Dont leave it blank
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Practice

• Review (on separate sheet of paper)
• Electron Configuration
• Orbital Diagram
• Electron configuration worksheet

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Using the Periodic Table

• The last subshell in the electron configuration
  is one of these
• (row ) s (row 1) d
• (row ) p (row 2) f

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The f-block is inserted into to the d-block
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Electron configuration of O

• Atomic number of O 8 so neutral atom has 8 e

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Electron configuration of Co

• Atomic number of Co 27 so neutral atom has 27
  e

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Simplifying electron configurations

• Build on the atoms noble gas core
• He 1s2
• O 1s22s22p4
• O He2s22p4
• Ar 1s22s22p63s23p6
• Co 1s22s22p63s23p64s23d7
• Co Ar4s23d7

??
?
?
??
??
1s
2s
2p
??
??
??
??
??
??
??
??
??
??
??
?
??
?
?
1s
2s
2p
3s
3p
4s
3d
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Noble Gases

• Far right of the periodic table
• These elements are extremely unreactive or inert
• They rarely form compounds with other elements

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Noble Gas electron configurations

• What is the electron configurations for Neon
• Abbreviated way to write configurations
• Start with full outer shell then add on
• Br
• Ba

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Noble Gases

• Neon- emits brilliant light when stimulated by
  electricity neon signs- 4th most abundant
  element in the universe.
• Helium- light non reactive gas- used balloons-
  inexpensive, plentiful and harmless
• Radon- radioactive gas- can cause cancer-
  colorless, odorless emitted from for certain
  rocks underground

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Why are we doing all of this?

• Properties of atoms correlate with the number and
  energy of electrons
• Electron configurations are used to summarize the
  distribution of electrons among the various
  orbitals

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Practice

• 3-3 Practice
• Write the complete electron configurations and
  noble gas shorthand 1-4

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Practice

• Refer to a periodic table and write the electron
  configurations of these atoms.
• Write the configurations using shorthand
  notation.
• Zn
• I
• Cs

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The f-block is inserted into to the d-block
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Find the electron configuration of Au

• Locate Au on the periodic table

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Find the electron configuration of Au

• Au Xe
• The noble gas core is Xe

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Find the electron configuration of Au

• Au Xe6s2
• The noble gas core is Xe
• From Xe, go 2 spaces across the s-block in the
  6th row ? 6s2

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Find the electron configuration of Au

• Au Xe6s24f14
• The noble gas core is Xe
• From Xe, go 2 spaces across the s-block in the
  6th row ? 6s2
• Then detour to go 14 spaces across the f-block ?
  4f14
• note for the f-block, n row 2 6 2 4

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Find the electron configuration of Au

• Au Xe6s24f145d9
• The noble gas core is Xe
• From Xe, go 2 spaces across the s-block in the
  6th row ? 6s2
• Then detour to go 14 spaces across the f-block ?
  4f14
• note for the f-block, n row 2 6 2 4
• Finally go 9 spaces into the d-block on the 6th
  row ? 5d9
• note for the d-block, n row 1 6 1 5

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Electron configuration of ions

• What is an ion?
• How many electrons does Cl1- have?
• What is the electron configuration for the
  chloride ion?
• How many electrons does Ca2 have?
• What is the electron configuration for the
  calcium ion?
• What do you notice?

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Practice

• Draw the orbital diagram for sulfur.
• What ion does sulfur want to form and why?
• Draw the orbital diagram for Potassium.
• What ion does sulfur want to form and why?

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What does this mean

• Properties of atoms correlate with the number and
  energy of electrons
• Atoms like to have full outer shells.

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Why is this important

• Valence electrons
• Electrons in the outermost energy level
• Where all the action occurs

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Practice

• Whiteboard - Atomic Structure (continued)

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Team

• Write the electron configuration for silver.
• Write the noble gas configuration for silver.
• What element has the following electron
  configuration?
• 1s22s22p6 3s23p64s23d4

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Today we use aspects of line spectrum to identify
elements, compounds and mixtures?

• UV-Vis Spectrometer
• Distances and types of stars
• Blood test- carbon monoxide poisoning
• Mobile weapons detectors
• Chlorophyll

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How we determine these energy levels?