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A powerpoint compiled
by the best chemistry
teacher ever, Mr Soltmann,
and created by his first
period honors chemistry class.
Democritus
•Anicent Greek Philosopher
•Made first Atomic Theory
•Universe made of two
elements - atoms, and the
void in which they exist
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•Wrote books and
encyclopedias
•Plato dislikes his work in
Little Cosmology
•Was taught by Leucippus
http://www.mlahanas.de/Greeks/Bios/DemocritusN
aples.jpg
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
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Aristotle
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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.
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http://mrsvesseymathematicians.wikispaces.com/file/view/aristotl
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Atomism
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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 don’t 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
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http://www.detoxifynow.com/Images/atom1.jpg
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Theory of Four Elements
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• 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.
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Antoine Laurent Lavoisier
and
The Law of Conservation of Matter
by: Ryan Hall and Ben Sherman.
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.
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.
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
(Fe+S), 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
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
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.
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
Joseph Proust (1754-1826)
Proust was a renown French chemist of his time. He began studying
chemistry in his father’s apothecary at a young age. His most famous
hypothesis was the controversial idea of the Law of Definite
Proportions.
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
Law of Definite Proportions
• He used inorganic binary
compounds to test his hypothesis
– Ex: metallic oxides, sulfides,
sulfates
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• 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
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
Controversy of Proust’s Findings
• Proust’s 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
Impact on Modern Day Chemistry
• Proust’s 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
John Dalton
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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.
• 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.
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.
• 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.
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.
• 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.
-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.
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-Discovery of atoms
-He is known for:
-Plum pudding model
-Discovery of electron
-Discovery of isotopes
-Mass spectrometer
invention
-First m/e measurement
- Thomson (unit)
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What is it?
- A glass apparatus,
evacuated tube
- Has a partial vacuum
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- Negatively charged
cathode
- Positively charged anode
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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.
What happened next?
- An external magnetic field has an effect on the ray
-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.
-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
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Caroline and Nick
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• 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)
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• 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.
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• 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.
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• FOUND CHARGE OF ELECTRON!!!!!!!!!!!!!!
• Millikan was able to determine the kinetic energy of the ejected
electrons obey the formula Einstein proposed. (1/2mv2=hf-p)
• First to measure the charge accurately!
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• 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
Avogadro’s Number. (6.02 X 1023 ) AKA 1 Mole!
• He proved the electric charge is quantized.
Video Aid
•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
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
Before Rutherford’s 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
•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 foil’s atoms without being deflected (changing direction)
By: Caroline Gluck and Carly Saferstein
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
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
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
• 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
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
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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
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The Neutron Discovery
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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-Curie’s 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
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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
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Significance
• Chadwick’s 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
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.
Sources Democritus
• http://abyss.uoregon.edu/~js/ast123/lectures/loc04.html
• http://www.crystalinks.com/leucippus.html
• http://www.britannica.com/EBchecked/topic/337658/Le
ucippus
• http://cstl- csm.semo.edu/mcgowan/ch181/atomhist.htm
• http://improbable.org/era/physics/atom.html
• http://www.ucmp.berkeley.edu/history/aristotle.html
• http://www.webwinds.com/myth/elemental.htm
Bibliography Lavoisier
• https://reichchemistry.wikispaces.com/file/view/Antoine_lavoisier.jpg/146845315/Antoine_lavo
isier.jpg
• http://adamant.typepad.com/photos/uncategorized/2007/10/29/lavoisier_4.jpg
• http://www.cartage.org.lb/en/themes/sciences/chemistry/generalchemistry/energy/
lawofconservation/lawofconservation.htm
• http://upload.wikimedia.org/wikipedia/commons/4/44/Lavoisier-statue.jpg
• http://en.wikipedia.org/wiki/Law_of_conservation_of_mass
• http://chemistry.about.com/b/2010/08/26/this-day-in-science-history-august-26antoine-lavoisier.htm
• http://en.wikipedia.org/wiki/Antoine_Lavoisier
• http://www.lightandmatter.com/html_books/7cp/ch01/ch01.html#Section1.2
Sources
Wikipedia.org
Britannica.com
Fact-index.org
Citation (Dalton)
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•
•
•
•
•
http://en.wikipedia.org/wiki/Atomic_theory
http://en.wikipedia.org/wiki/Law_of_multiple_proportions
http://www.iscid.org/encyclopedia/Law_of_Multiple_Proportions
http://en.wikipedia.org/wiki/John_Dalton
http://www.universetoday.com/38193/john-daltons-atomic-theory/
http://www.google.com/images?um=1&hl=en&safe=active&client=safari&rls=en&biw
=1267&bih=680&tbs=isch%3A1&sa=1&q=atom&aq=f&aqi=g10&aql=&oq=&gs_rfai
=
Pictures: www,google.com
Information:
1. http://www.suite101.com/content/millikan-oil-dropexperiment-a124624
2. http://en.wikipedia.org/wiki/Oil_drop_experiment
3. http://en.wikipedia.org/wiki/Robert_Millikan
4. http://ffden2.phys.uaf.edu/212_fall2003.web.dir/ryan_mcallister/slide3.h
tm
5. http://www.britannica.com/EBchecked/topic/382908/Millikan
-oil-drop-experiment
http://www.aip.org/history/electron/jjthomson.htm
http://en.wikipedia.org/wiki/J._J._Thomson
http://www.wwnorton.com/college/chemistry/gilbert2/tutorials/inter
face.asp?chapter=chapter_02&folder=cathode_ray
http://www.aip.org/history/electron/jjhome.htm
http://nobelprize.org/nobel_prizes/chemistry/laureates/1
908/rutherford-bio.html
http://en.wikipedia.org/wiki/Ernest_Rutherford
http://www.orcbs.msu.edu/radiation/resources_links/hist
orical_figures/rutherford.htm
http://en.wikipedia.org/wiki/Geiger–
Marsden_experiment#Conclusions
By: Caroline Gluck and Carly Saferstein
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/dp
32ne.html