Review of Atomic Theory

1
Review of Atomic Theory
A powerpoint compiled by the best
chemistry teacher ever, Mr Soltmann, and created
by his first period honors chemistry class.
2
Democritus

• Anicent Greek Philosopher
• Made first Atomic Theory
• Universe made of two elements - atoms, and the
  void in which they exist
• Wrote books and encyclopedias
• Plato dislikes his work in Little Cosmology
• Was taught by Leucippus

• http//www.mlahanas.de/Greeks/Bios/DemocritusNaple
  s.jpg

3
Leucippus

• Relatively unknown
• Born at Miletus or Abdera
• Cotemporary of Zeno, Empedocles, and Anaxagoras
• Credited with originating the theory of atomism
• Taught Democritus
• Fame overshadowed by student

http//reich-chemistry.wikispaces.com/file/view/Le
ucippus.jpg/147027201/Leucippus.jpg
4
Aristotle

• 384 - 322 BC
• Born in Stagira
• Taught by Plato, but opposed ideas
• First tutored in Medicine, but switched to
  Philosophy with Plato
• Worked with subjects like Biology, Physics,
  Morals, Aesthetics, and Politics.
• Most considered to be incomplete works.

http//mrsvesseymathematicians.wikispaces.com/file
/view/aristotle_stone.jpg/122672537/aristotle_ston
e.jpg
5
Atomism

• Leucippus originated Atomism
• Everything is composed of unbreakable homogenous
  elements called atoms
• Constantly in motion and through collisions and
  regroupings, formed various compounds through
  which everything was made
• There are an infinite amount of atoms
• Democritus theorized that all mater is composed
  of tiny units called Atoms.
• They dont change, but move in space to combine
  to form all objects
• Characteristic of object determined by shape of
  object. For example ,sweet things are made of
  smooth atoms, bitter made from sharp

http//www.detoxifynow.com/Images/atom1.jpg
6
Theory of Four Elements

• Was developed by Geek philosopher by Empedocles
• All matter (including atoms) made up of fire,
  earth, water, and air
• Could constantly cut matter
• Was accepted over the concept of Atomism
• Did not believe in atomism
• Aristotle believed in theory of four elements.
• Influenced by thought of the existence of Greek
  Gods
• Fire and Water are opposites, and Earth and Air
  were opposites
• Each of the opposites was considered to have
  existed in ideal form apart from Earth, and a
  mixed, impure form away from Earth.

http//reich-chemistry.wikispaces.com/file/view/is
t2_700000_four_elements_vector.jpg/31319395/ist2_7
00000_four_elements_vector.jpg
7

• Antoine Laurent Lavoisier
• and
• The Law of Conservation of Matter
• by Ryan Hall and Ben Sherman.

8
Background Information

• Born Antoine Laurent Lavoisier, he was known as
  the Father of Modern Chemistry, and sometimes
  Physics as well.
•  
• Born in Paris, France, on August 26th, 1743
•  
• Received a large fortune at the age of five due
  to his mother's death.
•  
• Attended the Mazarin College in 1754 to 1761,
  studying chemistry, botany, astronomy, and
  mathematics.
•  
• In 1771, at the age of 28, he married Marie-Anne
  Pierrette Paulze, who was only 13 at the time.
•  
• Paulze proved to be very helpful, and was able to
  translate documents, create drawings of many
  laboratory experiments, and edit and publish
  Lavoisier's memoirs. 
•  
•  Paulze also hosted parties, where scientists
  discussed their new ideas.
•  

9
Background Information

• Lavoisier discovered the elements of oxygen and
  hydrogen, helped in the creation of the metric
  system, and wrote the first extensive list of
  elements.
•  
• He also discovered the importance of the role of
  oxygen in combustion, and that diamonds and
  graphite were both forms of the same element,
  carbon.
•  
• On May 8th, 1794, Lavoisier was tried for 
  defending foreign born scientists from having to
  forfeit their freedom and possessions in France.
•  
• Later that day, he was guillotined for being a
  traitor, dieing at the age of 50.
•  

10
The Law Of Conservation of Matter

• "During an ordinary chemical change, there is no
  detectable increase or decrease in the quantity
  of matter."  
•  
• This law is also referred to as the law of
  conservation of mass
• This means the mass of a substance before a
  reaction takes place is always the same as the
  mass of the reactants
• For example If you combine the reactants Iron
  and Sulfur (FeS), the product would still be
  made of iron and sulfur, just in a different
  chemical form.
•  
• After the reaction takes place, the mass of the
  iron and sulfur will be the same as that of the
  iron sulfide

11
The Law (contd.)

• Originally, the Law of Conservation of Mass was
  not accepted in the world.
•  
• This was because, for example, when you would
  burn an item, it would weigh less after the
  reaction took place.
•  
• People had not realized that mass was lost
  through oxygen. 
• Once reactions could be completed and weighed in
  a vacuum, the law could be successfully proved. 
• When the gas was in a vacuum, it could not
  accidentally escape.  
•  
• Also, now that it is sealed in a container, the
  gas could now be weighed

12
Significance of Law of Conservation of Mass

• This discovery of the Law of Conservation of Mass
  was an important step in changing alchemy to
  modern chemistry.
• Because of this new knowledge, scientists had to
  go back and recheck their previous mass
  measurements that they took when they performed
  past experiments.
•  
• Many of these previously-taken measurements
  proved to be incorrect.
• This law was the basis for many later scientific
  discoveries. 
•  
• Without this law, the Law of Conservation of
  Energy, another important scientific discovery,
  would not exist.

13
Significance of Law of Conservation of Mass

• Nowadays, the Law of Conservation of Mass is
  common knowledge for all scientists.
•  
• The scientific society now understands how,
  during a reaction, matter only changes state,
  between being a solid, liquid, or gas.
•  
• Before this law was created, scientists didn't
  completely understand that gases were just
  another state of matter. 
•  
• They also hadn't tried performing reactions in
  sealed containers to determine whether gases were
  being consumed from or released into the air. 
•  
• Lavoisier's findings proved that they knew less
  than they thought

14
Joseph Proust (1754-1826)

• Proust was a renown French chemist of his time.
  He began studying chemistry in his fathers
  apothecary at a young age. His most famous
  hypothesis was the controversial idea of the Law
  of Definite Proportions.

15
Background Info (cont.)

• He began his career as a pharmacist at the
  Salpêriére Hospital in Paris, France
• He abandoned this position and entered the field
  of chemistry
• He taught chemistry at the Musé, a private
  scientific institution in Paris
• He also taught at the Chemistry School in
  Segovia, Spain

16
Law of Definite Proportions

• He used inorganic binary compounds to test his
  hypothesis
• Ex metallic oxides, sulfides, sulfates
• This hypothesis stated that chemical substances
  could only join together to form a small number
  of compounds
• These compounds had components that combined in
  fixed proportions based on their weight

17
Law of Definite Proportions (cont.)

• Pure compounds contain elements that combine in
  definite proportions to each other
• For example Oxygen will always be 8/9 the mass
  of pure water, while hydrogen will always be 1/9
  the mass
• This idea was published in 1795

18
Controversy of Prousts Findings

• Prousts hypothesis was rejected by other
  chemists of his time
• Claude Louis Berthollet, another French chemist,
  believed that elements could combine in any
  proportion
• This shows that they had not yet discovered the
  difference between pure chemical compounds and
  mixtures

19
Impact on Modern Day Chemistry

• Prousts ideas helped contribute to the atomic
  theory constructed by John Dalton promoted in
  1803
• Today, it has been proven that there are certain,
  rare exceptions to the Law of Definite
  Proportions
• Ex iron oxide wüstite

20
John Dalton

• John Dalton (6 September 1766 - 27 July 1844) was
  an English chemist, meteorologist and physicist
• Best known for his pioneering work in the
  development of modern atomic theory, and his
  research into color blindness.

21

• John Dalton was born into a Quaker family at
  Eaglesfield in Cumberland, England.
• Dalton's first publication was Meteorological
  Observations and Essays (1793), which contained
  the seeds of several of his later discoveries.
• A second work by Dalton, Elements of English
  Grammar, was published in 1801.

22
Atomic theory

• Is a theory of the nature of matter, which states
  that matter is composed of discrete units called
  atoms, as opposed to the obsolete notion that
  matter could be divided into any arbitrarily
  small quantity.
• John Dalton did more experiments to prove this
  and soon found that he could use his theory and
  understanding of gases and the elements to find
  out the atomic weight of each element.

23

• Elements are made of the smallest particles
  called atoms.
• All atoms for a particular element are identical.
  
• Atoms of different elements can be told apart by
  their atomic weight.
• Atoms of different elements can combine in a
  chemical reaction to form chemical compounds in
  fixed ratios.

24
Law of multiple proportions

• The law is based of The law of definite
  proportions
• Is one of the fundamental laws and was first
  discovered by the John Dalton in 1803.
• Dalton experimented with a gas called nitric
  oxide (NO) and oxygen (O). He reacted them
  together to produce a third type of gas. The
  results were determined by the proportions or
  ratios of the two reacting gasses.

25

• The law states that when chemical elements
  combine, they do so in a ratio of small whole
  numbers.
• If two elements form more than one compound
  between them, the ratios of the masses of the
  second element to a fixed mass of the first
  element will also be in small whole numbers.

26
JJ Thomson

• Born on December 18, 1856
• Received a scholarship to one of the most
  prestigious colleges in England, Trinity College.
• He received a BA in Math
• He has one son named George and a daughter named
  Joan.

27
Preceding Chemistry Discoveries

• Discovery of atoms

28
JJ Thomson

• He is known for
• Plum pudding model
• Discovery of electron
• Discovery of isotopes
• Mass spectrometer invention
• First m/e measurement
• Thomson (unit)

29
Cathode Ray

• What is it?
• A glass apparatus, evacuated tube
• Has a partial vacuum
• Negatively charged cathode
• Positively charged anode

30
(No Transcript)
31
The Experiment

• What happened?
• Electricity passes through a tube from two
  electrodes
• Through the cathode and anode
• A current is created, which is called cathode ray
• The ray goes from one side of the tube to the
  other
• When this occurs a florescent spot and coating
  on the opposite side is shown.

32
The Experiment Continued...

• What happened next?
• An external magnetic field has an effect on the
  ray

33
The Results

• This proved that the Cathode Ray has a mass and a
  negative charge.
• This developed the mass to charge ratio of
  particle m/q
• He realized that the rays were particles that
  were smaller than the atom (he called these
  corpuscles)
• Other scientists later proved that his findings
  were electrons, making him the first to discover
  this negatively charged particle.

34
The Results

• The discovery lead to the Plum Pudding Model
• Which then lead to the Bohr Model of the atom
• His discoveries still effect modern ideas and
  technologies
• Computer, Tv
• - This started a whole new era of scientific
  discovery and greatly impacts all of our lives

35
Robert Milikan
Caroline and Nick
36
HIS LIFE

• He was born March 22, 1868 in Morrison Illinois.
• He went to Oberlin college and then he got his
  doctorate in physics from Columbia.
• Professor at University of Chicago
• He became the Caltech President (California
  Institute of Technology)

37
HIS LIFE CONTINUED

• He won the noble prize for finding the charge on
  an electron
• Millikan has a middle school named after him in
  Los Angeles. It is known as Millikan Middle
  School.
• He did work with the Photoelectric Effect
• He died of heart attack on December 19, 1953.

38
The Oil Drop Experiment

• The goal of this was to find the charge of an
  electron.
• The experiment entailed balancing the downward
  gravitational force with the upward buoyant and
  electric forces on tiny charged droplets of oil
  suspended between two metal electrodes.

39
How Does It Work?
40
What Does This All Mean?

• FOUND CHARGE OF ELECTRON!!!!!!!!!!!!!!
• Millikan was able to determine the kinetic energy
  of the ejected electrons obey the formula
  Einstein proposed. (1/2mv2hf-p)
• First to measure the charge accurately!

41

What Does This All Mean?

• His ingenious experiment displayed that a charge
  on a single electron was the smallest possible
  amount of charge.
• He used his results to inspire himself to develop
  the value of Avogadros Number. (6.02 X 1023 )
  AKA 1 Mole!
• He proved the electric charge is quantized.

42
Not Getting The Big Picture?
Video Aid
43
Rutherford
Ernest

• Born on August 30, 1871 in New Zealand
• Went to college and graduated with a degree in
  Mathematics and Physical Science
• He won scholarship allowing him to further his
  education at Trinity college, studying under
  scientist JJ Thompson
• He is known as the Father of Nucelar Physics
• Won the Nobel Prize for Chemistry in 1908

By Caroline Gluck and Carly Saferstein
44
Rutherford
Ernest

• His experiments consisted of
• Developing terms alpha and beta to indicate
  two types of radiation and later a third type of
  radiation, gamma rays
• Collaborating with Fredrick Soddy on changing an
  elements with radioactive decay
• Discovered radioactivity could be used to
  determine the age of a substance (radioactive
  dating) such as the Earth

By Caroline Gluck and Carly Saferstein
45
BEFORE
The Gold Foil Experiment

• Before Rutherfords experiment, the model of an
  atom was not properly understood and thought of
  as plum pudding
• The negative charges were in small grouping
  throughout the atom surrounded by a pool of
  positive charges
• His experiment led to the discovery of the atomic
  nucleolus

By Caroline Gluck and Carly Saferstein
46
The Gold Foil Experiment

• The experiment shot a tiny, dense beam of
  positive alpha particles at thin metal foils
• His hypothesis was that the bean would pass
  straight through the foils atoms without being
  deflected (changing direction)

By Caroline Gluck and Carly Saferstein
47
The Gold Foil
Experiment

• The experiment involved
• A block of radium inside a lead box
• with a hole for the alpha to shoot out of
• A thin gold foil to
• interrupt the beam of
• alpha particles
• A circular florescent
• screen detecting
• alpha particle
• beams

By Caroline Gluck and Carly Saferstein
48
The Gold Foil Experiment

• The experiment involved
• The deflected beams were unexpected and did not
  fit

• the hypothesis that expressed the properties of
  the plum pudding atomic model
• He found that the alpha particles were being
  deflected by something small, dense and positive-
  the nucleus
• His experiment led to the discovery of the atomic
  nucleolus

By Caroline Gluck and Carly Saferstein
49
The Gold Foil Experiment
Significance

• Rutherford proved the Plum Pudding atomic model
  wrong
• Negatively charged groupings did not consist of
  large enough masses or charges to strongly
  deflect the alpha beam
• Positive pudding did also not consist of large
  enough masses or charges to strongly deflect the
  alpha beam

By Caroline Gluck and Carly Saferstein
50
The Gold Foil Experiment
Significance

• Invented theory of the that much of atoms mass
  is in dense ball in the center, now known as the
  nucleolus
• He proposed that outside of dense ball was mostly
  empty space
• From his discovery, newer and more accurate
  models of the atom were able to be created

By Caroline Gluck and Carly Saferstein
51
Background Information

• James Chadwick discovered the neutron in 1932
• Born in 1891 in Manchester, England
• Graduated from Manchester University
• Was a prisoner of war in Germany at the beginning
  of World War I because of a scholarship
• When he left the war, he went back to England to
  rejoin the mentor of his undergraduate days
  Ernest Rutherford

52
Background Information

• Rutherford appointed him the job of assistant
  director of radioactive research at Cavendish
  Laboratory in Cambridge
• He was married to Aileen Stewart- Brown and had
  two daughters
• He worked on the Manhattan project which was the
  first time an atomic bomb had been produced
• He died in 1974

53
The Neutron Discovery

• Chadwick mainly studied atomic disintegration
• After Rutherford discovered the proton, it was
  believed that there had to be another subatomic
  particle in the nucleus, as the atomic mass did
  not match up with the atomic number
• Chadwick originally believed that what he called
  the neutron was not actually its own subatomic
  particle, but a proton and an electron together
• Chadwick caught wind of Frederic and Irene
  Joliot-Curies experiments and decided to use
  them to see if he could find the neutron
• The experiments were a success, and he discovered
  that the neutron did exist, with a mass of about
  .1 more than the proton

54
The Neutron Discovery (Cont)

• Chadwick titled his book Possible existence of
  the Neutron and it received a Nobel Prize
• His findings were quickly accepted
• Werner Heisenberg realized that the neutron had
  to be its own subatomic particle and that it was
  not a proton-electron pair
• Physicists soon found that the neutron made an
  ideal "bullet" for bombarding other nuclei, as
  unlike charged particles, it was not pushed away
  by similarly-charged particles and could smash
  right into the nucleus
• Neutron bombardment was applied to the uranium
  atom, splitting its nucleus and releasing the
  huge amounts of energy predicted by Einstein's
  equation E mc2

55
Significance

• Chadwicks discovery made possible the fission of
  uranium 235 and the creation of the atomic bomb
• His discovery helped other scientists to figure
  out the anatomy of the atom.
• He helped to develop the atomic bombs that
  destroyed two Japanese cities and ended WW2
• He was an advocate of the dangers of radiation
  and co-authored a book, Radiations about
  Radioactive Substances, about the topic

56
Significance (cont.)

• He was awarded the Hughes Medal of the Royal
  Society in 1932
• He won Nobel Prize for Physics in 1935.
• He was knighted in 1945.

57
Sources Democritus

• http//abyss.uoregon.edu/js/ast123/lectures/loc04
  .html
• http//www.crystalinks.com/leucippus.html
• http//www.britannica.com/EBchecked/topic/337658/L
  eucippus
• http//cstl- csm.semo.edu/mcgowan/ch181/atomhist.h
  tm
• http//improbable.org/era/physics/atom.html
• http//www.ucmp.berkeley.edu/history/aristotle.htm
  l
• http//www.webwinds.com/myth/elemental.htm

58
Bibliography Lavoisier

• https//reich-chemistry.wikispaces.com/file/view/A
  ntoine_lavoisier.jpg/146845315/Antoine_lavoisier.j
  pg
•  
• http//adamant.typepad.com/photos/uncategorized/20
  07/10/29/lavoisier_4.jpg 
•  
• http//www.cartage.org.lb/en/themes/sciences/chemi
  stry/generalchemistry/energy/lawofconservation/law
  ofconservation.htm
•  
• http//upload.wikimedia.org/wikipedia/commons/4/44
  /Lavoisier-statue.jpg 
•  
• http//en.wikipedia.org/wiki/Law_of_conservation_o
  f_mass
•  
• http//chemistry.about.com/b/2010/08/26/this-day-i
  n-science-history-august-26-antoine-lavoisier.htm
•  
• http//en.wikipedia.org/wiki/Antoine_Lavoisier 
•  
• http//www.lightandmatter.com/html_books/7cp/ch01/
  ch01.htmlSection1.2

59
Sources
Wikipedia.orgBritannica.comFact-index.org
60
Citation (Dalton)

• http//en.wikipedia.org/wiki/Atomic_theory
• http//en.wikipedia.org/wiki/Law_of_multiple_propo
  rtions
• http//www.iscid.org/encyclopedia/Law_of_Multiple_
  Proportions
• http//en.wikipedia.org/wiki/John_Dalton
• http//www.universetoday.com/38193/john-daltons-at
  omic-theory/
• http//www.google.com/images?um1hlensafeactiv
  eclientsafarirlsenbiw1267bih680tbsisch3
  A1sa1qatomaqfaqig10aqloqgs_rfai

61
The Experts

• Pictures www,google.com
• Information
• http//www.suite101.com/content/millikan-oil-drop-
  experiment-a124624
• http//en.wikipedia.org/wiki/Oil_drop_experiment
• http//en.wikipedia.org/wiki/Robert_Millikan
• http//ffden-2.phys.uaf.edu/212_fall2003.web.dir/r
  yan_mcallister/slide3.htm
• http//www.britannica.com/EBchecked/topic/382908/M
  illikan-oil-drop-experiment

62
Sources
http//www.aip.org/history/electron/jjthomson.htm
http//en.wikipedia.org/wiki/J._J._Thomson
http//www.wwnorton.com/college/chemistry/gilber
t2/tutorials/interface.asp?chapterchapter_02fold
ercathode_ray http//www.aip.org/history/electr
on/jjhome.htm
63
Work Cited
http//nobelprize.org/nobel_prizes/chemistry/laure
ates/1908/rutherford-bio.html http//en.wikipedia
.org/wiki/Ernest_Rutherford http//www.orcbs.msu.
edu/radiation/resources_links/historical_figures/r
utherford.htm http//en.wikipedia.org/wiki/Geiger
Marsden_experimentConclusions
By Caroline Gluck and Carly Saferstein
64
Citations

• http//www.vzhang.com/vzfiles/james_chadwick.htm
• http//www.light-science.com/chadwick.html
• http//www.nndb.com/people/728/000099431/
• http//www.pbs.org/wgbh/aso/databank/entries/dp32n
  e.html

65
THE END