Chapter 5 Section 5'1

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Chapter 5Section 5.1

• Electrons in Atoms

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Light Quantized Energy

• The light produced by certain elements when
  burned shows that the chemical behavior is
  related to the arrangement of electrons in the
  elements atom

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ELECTROMAGNETIC RADIATION

• Form of energy that move in waves as it travels
  at the speed of light. Visible light microwaves,
  x-rays, TV and Radio waves.

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WAVE LENGTH

• The distance from one wave to the next.

Wave Length
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AMPLITUDE

• The waves height.
• Measure from the origin to the Crest

Crest-Top
Amplitude
Bottom-Trough
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FREQUENCY

• The number of waves that pass a given point per
  second. HzHertz
• 1 Hz 1 wave per second

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• Wavelength and frequency are inversely related
• When one goes up, the other goes down
• Sketch diagram bottom of page 119

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THE Speed of Light

• 3 x 108m/s
• 300,000,000meters per second
• c Speed of Light
• c wavelength Frequency
• C v

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ELECTROMAGNETIC SPECTRUMEM

• All forms of electromagnetic waves arranged by
  the wavelength and frequency of the waves.
• Short wavelengths bend more than long

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VISIBLE LIGHT

• ROY G. BIV
• Red- Orange- Yellow- Green- Blue- Indigo- Violet
• Energy increases with increasing frequency
• Sketch chart bottom of page 120

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Calculate Wavelength

• c v c3 x 108 m/s
• Frequency 3.44 x 109 Hz
• c / v
• 3 x 108 3.44 x 109
• 8.7 x 10-2 meters
• Work problems 1-4, page 121

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Particle Nature Of Light

• The wave-model of light does not explain every
  aspect of light
• The Quantum Concept explains the different colors
  produced at different temperatures

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• Quantum- The minimum amount of energy that can be
  lost or gained by an atom. A small specific
  amount or packet of energy
• Equantum
• v Frequency
• h Plancks Constant
• 6.626 x 10-34 joules (j)

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• Plancks theory states that , for a given
  frequency, matter can emit or absorb energy only
  in whole number multiples of hv 1hv, 2hv,etc..
• Partial packets or quantums are not possible

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The Photoelectric Effect

• Occurs when electrons called photo-electrons are
  emitted from a metals surface when light of a
  certain frequency shines on the surface of the
  metal.

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SOLAR POWERED

• Photoelectric cells in a solar powered calculator
  convert the energy of light into electric energy
  using the photo-electric effect.

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• When light of a certain frequency strikes the
  photoelectric cell an electron is released.
  Moving electrons Electricity.
• Solar Powered instruments use light to change
  light to electricity

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• Albert Einstein- Developed the current theory
  that light has both Wavelike and Particle
  Characteristics.
• Light moves in waves and as a stream of particles
  or bundles of energyPhotons

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PHOTON

• Particle of electromagnetic radiation with no
  mass that carries quantum of energy moving at the
  speed of light.

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Atomic Emission Spectra

• Set of frequencies of the electromagnetic waves
  emitted by atoms of a certain element
• When electricity is passed through Neon Gas-
  light is produced by the excited atoms of neon-
  Neon Signs
• Each elements EMS is unique used for ID of the
  element

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Chapter 5

• Section 5.2

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Bohr Model of the Atom

• Bohrs Model of the atom allowed for only certain
  energy states.
• Ground State- The lowest allowable energy state
  of a certain atom

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• Bohrs Atomic Model had electrons in different
  energy orbits around the nucleus.
• The first orbit had the lowest energy. More
  energy added to the atom the electron can move up
  to the next energy level.

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• When the electron moved back down an orbit it
  would release energy as light
• Each energy level would release a different
  light.
• You can only move from one energy level to the
  next

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Quantum Mechanical Model of the Atom

• Basically said that the electrons moved in wave
  motion in their orbits around the nucleus
• All moving particles have wave characteristics

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Heisenberg Uncertainty Principle

• It is impossible to know precisely both the
  velocity position of a particle at the same
  time.

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• The action and energy used to try to locate a
  particle would actually change the particles
  position and velocity. So the actual process of
  looking for the particle will change its energy
  level

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• The Quantum Mechanical model of the atom limits
  an electrons energy to certain values but makes
  no attempt to describe the electrons path around
  the nucleus

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• Atomic Orbital- 3 dimensional region around the
  nucleus of an atom that shows the electrons
  probable location
• The Atomic Orbital for electrons is fuzzy. It can
  be in many places and it is moving at the speed
  of light.

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• The Atomic Orbital does NOT have a defined size
  because the electron can be in so many places
• The orbital is drawn to contain 90 probability
  of where the electron might be.

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Principal Quantum Numbers

• Indicates the relative size and energy of atomic
  orbitals (n)
• As (n) increases the orbital becomes larger and
  the electron spends more time further away from
  nucleus

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Principal Energy Levels

• The lowest Principal Energy level has a value of
  n1
• This is the ground state for that atom.
• These are sphere shaped and are s-orbitals 1s
  2 s etc...

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Energy Sublevels

• The Principal energy levels contain Sublevels.
• Principal energy level 1 contains 1 sublevel
• Principal energy level 2 contains 2 sublevels.

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• Energy Sublevels are labeled s, p, d or f.
• S are Spherical
• P orbitals - dumbbell shaped
• D f orbitals may have different shapes

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• Each orbital may contain at most 2 electrons
• Principal energy level 1 consists of 1s sphere
  shaped orbital
• PEL 2 consists of 2s orbital 2p orbital

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• 2s orbital is sphere shaped and larger than the
  1s
• The 2 p orbital consists of 3 dumbbell shaped
  orbitals 2px 2py 2pz
• PEL 3 Consists of 3 sublevels 3s , 3p , 3d

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• 3s larger sphere shaped orbital
• 3p 3px 3pz 3py
• 3d dxy, dxz, dyz, d x2-y2, dz2
• PEL4 4s, 3p, 3d and a 4f that consists of seven
  orbitals of equal energy

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Chapter 5

• Section 5.3

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ELECTRON CONFIGURATION

• The arrangement of electrons in atoms follows a
  few simple rules

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• Electrons in an atom tend to assume the
  arrangement that gives the atom the lowest
  possible energy.
• This is the Ground State
• This is the most stable state

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Aufbau Principal

• Each electron occupies the lowest energy orbital
  available
• Each energy sublevel has equal energy
• S is the lowest energy sublevel
• Then the p sublevel, then d and then f

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Pauli Exclusion Principle

• An electron can spin in 1 of 2 directions
• Either or
• If 2 electrons are sharing an energy level they
  must have opposite spins.

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Hunds Rule

• Single electrons with the same spin must occupy
  each equal energy orbital before additional
  electrons with opposite spins can occupy the same
  orbital with another electron in that energy level

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Electron Configuration Notations

• Hydrogen 1 electron 1s1
• Helium 2 electrons 1s2
• Lithium 3 electrons 1s2 2s1
• Beryllium 4 electrons 1s2 2s2
• Boron 5 electrons 1s2 2s2 2p1
• Carbon 6 1s2 2s2 2p2

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Valence Electrons

• The Electrons that determine the Chemical
  Properties of an element.
• The electrons that control how that element
  reacts

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• Valence Electrons- are the electrons in the outer
  most Principal energy Levels or orbital.
• These are the only electrons involved in the
  chemical reaction

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• The Valence Electrons determine how the element
  will chemically react with other elements.
• Elements with the same number of valence
  electrons react the same way

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Electron Dot Structures

• The use of the elements symbol along with dots to
  represent the Valence Electrons for that element.

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Aluminum Atomic 13 13 electrons / 13
protons Electron configuration 1s2 2s2 2p6
(3s2 3p1) has 3 valence electrons 3 Dots to
represent Valence electrons
Al