Science pdf 2

Discovery of the Atoms
By Jennifer Kim
Friday, November 4, 2011

Rutherford
• Rutherford was a New Zealand scientist, he discovered the structure of the atom with Niel Bohr. It is
known as the Rutherford-Bohr Theory of Atomic Structure.
• One of his experiment was, which he shot relatively large, charged particles called the “Alpha
particles” at a thin gold foil. Through this project, he found the particles passing directly through the
foil but came off at odd angles. By this result, Rutherford concluded that each atom was mostly
empty space with dense region (central mass) in positive charge.
• However, he made an serious ﬂaw that electrons needed to orbit, but his analysis of energy were
made when an electron dropped from a higher energy orbit to a lower energy orbit. This doesn’t
make the orbit hold up the atoms. So, he wasn’t able to get the best result out of his experiment of
understanding the atom.

Who is Niels Bohr?
• Niels Bohr focused on researching the structure of the atom, and completed
the structure at 1913.
• Niels Bohr introduced the theory of electrons traveling around the atom’s
nucleus, only in discrete orbits which did not emit radiation. Which means
electron moves to a higher orbit with larger radius, absorbing the radiation.
• He also introduced that electrons could drop from a higher-energy orbit to
a lower one, light quantum of separate energy. This is the basis for
quantum theory.
• He also described the Periodic Table, and that nucleus as a compound
structure.
• While he was traveling to the United States, he immediately came up with
the theory that the rare uranium isotopes 235 are ﬁssionable by the slow
neutrons. However, isotope 238 cannot. Isotope: forms of same elements
with equal numbers of proton, but different neutrons in nuclear.
• During his time for understanding how to make Atomic bomb, he was
disturbed by escaping the invasion of Nazis in the World War II. His family
was half Jew, and escaped to Denmark then Sweden.
Bohr’s atomic
models form World
Book Encyclopedia
(1999 edition)

J J Thomson
• J J Thomson is scientist from England, who were honored for researching the discharge of
electricity in gases. He was the youngest and the third Cavendish Professor with James Clerk
Maxwell (who created the basic equations of electromagnetism).
• He made many important experiments on electromagnetism and atomic particles, such as
creating the “cathode ray tube.” It is a vacuum tube containing electron gun with the source of
electrons. This is the move and deﬂect the electron beam in order to show images in form of
light.
• His experiment creation were made with simpler materials and bad quality, which gave him
struggles to understand the result. The days back then, didn’t have the developed technology as
it is today. So the materials were a little in-functional Finally, he proved that the negative charge
and the ray are inseparable and twisted together.

John Dalton
• John Dalton was a scientist who worked and focused on the behavior and properties
of gases.
• John Dalton worked on experiments which proved that the understandings of gas
and the elements were used to ﬁnd out the atomic weight of each element.
• John Dalton’s performed experiments were well done, but he did not know about
their structure. Which he knew his result will be something fundamental.
John Dalton's Original Table of Atomic
Weights

Democritus
• Democritus, known as the ‘laughing philosopher’ because of his importance on the value of ‘cheerfulness,’ he was one of
the two founders of ancient atomist theory.
• He was a philosopher. Philosophers are people who think about the world, including the atoms. However, he studied many
things other than atoms. Such as, animals, plants, weather, and stars.
• He found that there were inﬁnite number of different types of atoms. They were kinds of shape and size which were made
from the same stuff. So how the substance was solid or liquid, hot or cold, spicy or sweet, he thought they were all because
of the appearance of atoms.
• However, his limitation was that he didn’t do any experiments or have the equipments to. He didn’t have the special
microscope to see the atoms, so he had to invent with his own imaginations. It was also too old back then, which was
harder to discover new things on their own.

Global Issue of Atoms
• Electricity from: Nuclear Power “Are they really
necessary?”
• These nuclear power plants are fueled by uranium, this
naturally occurs in the Rocky Mountains, countries such
as Canada, Australia, and South Africa.
• The energy is stored in uranium atoms and it makes the
nuclear power possible.
• The nuclear reaction generates heat to generate electricity,
which is like fossil fuels; it is an ﬁnite non-renewable
resource.
• We need them for radioactive materials, for treatments in
medicine, radiography, to remote locations, space
applications, and ﬁnally for food irradiation.

Beneﬁts and Limitations
• Even though they don’t generate air pollutants
(sulfur dioxide, carbon dioxide, nitrogen oxides), the
operation of nuclear power result in environmental
impacts (air emissions). Their air emissions are not
similar of those fossil plants, but they release small
amounts of airborne radioactive gasses.
• So does the nuclear plants that works upon water, it
will impact water resources, aquatic habitats, and
ﬁsh.
• The radioactive wastes from the nuclear power, risks
health and will be stored for centuries.

Environmental
• This is an issue that people all over the
world have. The Nuclear power made by
uranium is in only little way of carbon
emissions. The single nuclear power plant
can generate so much electricity, with a
long life span. However, toward the
environment, the process of mining
Uranium for nuclear power causes harm.
It destroys the landscape and releases
radioactive substances. The chemicals
during the process can leak into
groundwater.

Environments
Also, except the generation of nuclear fuel, they also involve carbon
emission in process. The most recent issues from today, Nuclear power
can bring out “Chernobyl.” It is when the radiation levels are every
where elevating normally from 10 to 100. It can also harm the water for
the coolings systems of the plants, and produce radioactive wastes.
Nuclear Powers can be a big use, but a very big harm towards our
environment.
Japan’s
Nuclear
Radiation

Economic
• The cost of building a nuclear power plants is
an expensive project, which requires good deal
of taxpayer money. The long planning and
building will invariably cost a lot. Also, the after
cost of this project will be huge. “Imagine” the
cost involved with storing nuclear waste for
thousands of years. How much will that be?
Sometimes, this project can be part of wasting
money for the countries.

Imagine..
-Human Health
Problems:
vomiting,headache,some loss of white blood
cells,nausea
Thousands of people
are sick from this

• Works Cited
"Chernobyl Legacy Lingers in Britain." Green Living Tips - a More
Environmentally Friendly Life. Web. 03 Nov. 2011. <http://
www.greenlivingtips.com/blogs/389/Chernobyl-legacy-lingers-in-
Britain.html>.
"Electricity from Nuclear Power." Power Scorecard Homepage.
Web. 03 Nov. 2011. <http://www.powerscorecard.org/
tech_detail.cfm?resource_id=7>.
"History of Atoms." NoBeliefs.com (Freethinkers). Web. 03 Nov.
2011. <http://nobeliefs.com/atom.htm>.
"J. J. Thomson's Cathode Ray Experiment." The Scientific Method,
Science, Research and Experiments. Web. 03 Nov. 2011. <http://
www.experiment-resources.com/cathode-ray.html>.

"John Dalton’s Atomic Theory." Universe Today — Space and
Astronomy News. Web. 03 Nov. 2011. <http://
www.universetoday.com/38193/john-daltons-atomic-theory/>.
"Nuclear Energy | Clean Energy | US EPA." US Environmental
Protection Agency. Web. 03 Nov. 2011. <http://www.epa.gov/
cleanenergy/energy-and-you/affect/nuclear.html>.
"Rutherford-Bohr Model | Radiation Protection | US EPA." US
Environmental Protection Agency. Web. 03 Nov. 2011. <http://
www.epa.gov/radiation/understand/rutherford.html>.
Book Source:
Pasachoff, Naomi. Niels Bohr Physicist and Humanitarian.
United States of America: Enslow, 2003. Print. Great Minds of
Science.

Thank You :)

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