Lab Activity This Week: B2WNL

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• Lab Activity This Week B2-WNL
• Chapter 8 Mallard HW quiz
• Due by 12 AM Tuesday 04/15
• Chapter 8 quiz end of class Tuesday 04/15
• Chapter 9 quiz end of class Tuesday 04/22
• Exam 4 (Chapters 8 and 9) on THU 04/24

Thursday, April 10 Spring 2008
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Photons Particles of Light
Used to move electron to higher energy state
Photon emitted as electron moves to lower energy
state
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Photons cont.

• Quantum leap or jump electron disappears from
  original location and reappears in final location
  never at positions in between

Energy is equal
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Energy in Bohr atom

• Energy required to leave ground state
• Absorb photon
• Heat
• Increases collisions
• Kinetic energy can excite atoms above the ground
  state

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Spectroscopy

• Atoms emit and absorb different photons
• Which photons depends on differences between
  energy levels in the atom
• Each atom (of one type of element) has a distinct
  set of energy levels, therefore, a unique pattern
  of photons
• Spectrum the photon pattern emitted by a
  particular kind of atom
• Used for identification of unknown sources
• Used to choose a desired output of light

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Spectroscopy cont.
Light from gaseous atoms is spread out by passing
through a prism (Lab 10)
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Spectroscopy cont.
Each atom produces a unique set of lines the
atomic fingerprint
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Spectroscopy cont.
Each atom produces a unique set of lines the
atomic fingerprint
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Periodic Table of the Elements
all colorless, odorless inert gases

• Systematizes elements
• Columns contain similar elements

soft, silvery elements
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Why the Periodic Table Works Electron Shells

• Patterns mirror arrangement of electrons in
  shells
• Pauli exclusion principle
• First shell 2 electrons, second shell 8 etc.

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Discovering Chemical Elements

• Electrolysis
• Mendeleev (1869)
• Current Periodic Table
• 112 elements
• 92 found in nature
• Everyday elements
• helium, carbon, aluminum, copper, gold
• 99 Earths solid mass 6 elements
• oxygen, silicon, magnesium, iron, aluminum, and
  calcium
• 99 of elements in the universe
• hydrogen (90), helium (9)
• Most elements in the body
• hydrogen, carbon, oxygen, nitrogen
• ( phosphorus, sulfur)

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Next Quantum Mechanics

• The laws of classical physics (gravity,
  electromagnetism) dont always work at the atomic
  and subatomic level
• For example, why are atoms energy levels
  quantized?
• How do we locate electrons in electron shells?
• A new set of laws for the very small needed to be
  formulated to explain the behavior of individual
  atomic and subatomic particles (and their
  interactions)