The Chemistry Boosters Study Guide Presentation

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The Chemistry Boosters Study Guide Presentation
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DIRECTIONS

• Any title that is underlined is a link. Click
  on it and it will take you where you want to go
• Icons that appear at the bottom of each page
  are also links. Click on them!

Home
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GOOD JOB!

• Now click on the icon below to go back to opening
  page of this presentation

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MENU TOPICS

• Laboratory Skills
• The Gas Laws
• Historical Development of the Atom

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Historical Development of the Atom

• Democritus
• John Dalton
• J.J. Thomson
• Ernest Rutherford
• Neils Bohr
• Wave Model

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NEILS BOHR
1885-1962
A divisible Atom

• He wondered about the exact location of electrons
  in an atom
• He concluded in 1913 that an electron had a
  certain amount of energy which keeps an electron
  moving around the nucleus in a region called an
  energy level.
• He described an atom much like the solar system
  in that electrons orbit around the nucleus in
  energy levels just as planets orbit around the
  sun

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Click here for an analogy
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Bohr Analogy

• An Onion
• If you cut an onion in half youll see rings.
  Bohrs model has rings called energy levels in
  which the electrons are located outside of the
  nucleus.

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WAVE MODEL or ELECTRON CLOUD-Modern Atomic Theory
A divisible atom

• In 1926, it was stated that it is impossible to
  know the exact location and motion of an electron
  or small particle Heisenburg Uncertainty
  Principle.
• Electrons dont orbit the nucleus in simple,
  well-defined paths. This is why chemists often
  show electron orbitals as cloudy regions. The
  more dots in the cloud, the more likely an
  electron would be found there.

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Click here for an analogy
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Electron Cloud Analogy

• If I placed a dark X on an airplanes moving
  propeller, do you think it would be easy to
  locate it exactly? What would it look like?

• Most likely you would see a dark blur where the
  X is moving around quickly. This relates to
  the electron cloud. You could estimate its
  location (top, middle, bottom of blade) but it is
  impossible to know exactly where the dark X is
  or an electron at one moment in time. Most
  likely it will be in the blurred area, however.

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DEMOCRITUS
An Indivisible Atom

• Almost 2500 years ago, the Greek philosopher
  Democritus proposed that all matter is composed
  of tiny particles. He called these particles
  atomos. You know them as atoms. Atomos is a
  Greek word meaning indivisible or impossible to
  be divided into parts.

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JOHN DALTON
(1766-1844)
English Schoolteacher
An Indivisible Atom
Daltons Atomic Theory (1803)

• All elements are composed of very small
  indivisible and indestructible particles called
  atoms.
• Atoms of the same element are exactly alike.
• Atoms of different elements are different.
• A given compound always has the same relative
  numbers and kinds of atoms. Atoms join in whole
  number ratios.
• Atoms are neither created nor destroyed in any
  chemical reaction.

Click here for an analogy
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Dalton Analogy

• A small atomic fireball
• An atom is small, spherical and the same
  throughout.

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ERNEST RUTHERFORD
New Zealand Scientist
A divisible atom

• In 1908, he performed his famous Gold Foil
  Experiment. Click on the underlined words for
  more information.
• His experiment proved that an atom is mostly
  empty space.
• It also proved that an atom has a small and dense
  positively charged center called a nucleus.

(1871-1937)
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Click here for an analogy
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Rutherford Analogy

• A peach
• A peach has a dense center known as the pit just
  like an atom has a dense but small center called
  the nucleus

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Gold Foil Experiment
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J.J. THOMSON
1856-1940
A divisible atom

• In 1897, Thomson used a Cathode Ray Tube (CRT) to
  prove that an atom had a subatomic particle known
  as an electron
• He believed that electrons were distributed
  throughout an atom
• This model is known as the Plum Pudding Model.
  Electrons are stuck throughout an atom just like
  plums are stuck throughout pudding. Plum Pudding
  is an English dessert

Click on the speaker to hear him speak about
electrons
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Click here for an analogy
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Cathode Ray Tube (CRT)
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Thomson Analogy

• Chocolate Chip Cookie
• Chocolate chips are distributed throughout a
  cookie just as electrons are distributed
  throughout an atom

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The Gas Laws

• Boyles Law
• Charles Law
• Gay-Lussacs Law
• Combined Gas Law

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THE COMBINED GAS LAW

• This equation expresses the relationship between
  pressure, volume, and temperature of a gas if the
  amount of a gas is fixed.

Ppressure Vvolume Ttemperature in KELVINS

• P1V1 P2V2
• T1 T2

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The number 1 initial conditions The number
2 final conditions
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GAY-LUSSACS LAW

• At constant volume, pressure varies directly with
  the KELVIN temperature
• KP/T
• Kconstant
• Ppressure
• TKelvin temperature

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CHARLES LAW

• At constant pressure, the volume of a given mass
  of a gas varies directly with the KELVN
  temperature
• KV/T
• Kconstant
• Vvolume
• Ttemp. in Kelvins

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BOYLES LAW

• When temperature remains constant, the volume of
  a gas is inversely proportional to its pressure
• PVK
• PPressure
• VVolume
• KConstant

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Laboratory Skills

• Lab apparatus
• Parts to a lab report
• Rules for significant figures
• Percent error
• Scientific notation
• Taking measurements and reporting the correct
  number of significant figures

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Lab Apparatus

• DIRECTIONS Pictures of various lab apparatus
  will appear on the next few screens. Guess the
  names of each picture and then advance to the
  next slide to see if you are correct. Be sure to
  know the correct spelling of each lab apparatus.

Begin Slide Show
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I. Name that apparatus!
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answers
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I. Name that apparatus answers
Burner
Erlenmeyer Flask
Beaker
Volumetric Flask
Forceps
Crucible tongs
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more apparatus
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II. Name that apparatus!
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answers
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II. Name that apparatus answers
Test tube
Crucible cover
Electronic balance
Graduated cylinder
Evaporating dish
funnel
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more apparatus
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III. Name that apparatus!
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answers
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III. Name that apparatus answers
Iron Ring
Pinch Clamp
Mortar Pestle
Measuring Pipettes
Test Tube Holder
Scoopula
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more apparatus
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IV. Name that apparatus!
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answers
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IV. Name that apparatus answers
Plastic wash bottle
Stirring rod with rubber policeman
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more apparatus
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V. Name that apparatus!
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answers
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V. Name that apparatus answers
Dropper pipette
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more apparatus
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VI. Name that apparatus!
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answers
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VI. Name that apparatus answers
Iron ring stand
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• CREDITS

• Designed by Karie L. Brewster
• For EDI 581 at SUNY Brockport
• Under the direction of Jerry Taylor
• Fall 2000

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