THALES
Thales lived about 600’s b.c.He was born in the city of Miletus (It is the Milet town in the city
of Aydın). The time of his life is roughly established by a few dateable events mentioned in
the sources and an estimate of his length of life. According to Herodotus, Thales once
predicted a solar eclipse.
Thales and geometry: There is a theorem in geometry called Thales’ theorem about similar
triangles.
This is thale’s theorem
Thales and the atomic theory:
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Aristotle: according to Thales the earth is superimposed upon water
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Thales: the primary building blocks of all things to be water.
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Therefore, he thought “things” as varying forms of one primary and ultimate
element.
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Of course, today we know that his ideas about water is wrong.
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However, he actually suggested the same working hypothesis of modern atomic
theory that all things are made up of atoms.
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Historically, it is very important for a philosopher to think that things have a common
building block.
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Based on this, many claim that Thales is the father of both philosophy and physics
JOHN DALTON
John Dalton (6 September 1766 – 27 July 1844) was an English chemist,
meteorologist and physicist. He is best known for his pioneering work in the
development of modern atomic theory, and his research into colour blindness
(sometimes referred to as Daltonism, in his honour).
Dalton's Atomic Theory
1) All matter is made of atoms. Atoms are indivisible and indestructible.
2) All atoms of a given element are identical in mass and properties
3) Compounds are formed by a combination of two or more different kinds of atoms.
4) A chemical reaction is a rearrangement of atoms.
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Dalton was even the first to make an attempt at creating a table of atomic
weights
Modern atomic theory is, of course, a little more involved than Dalton's theory but the
essence of Dalton's theory remains valid. Today we know that atoms can be destroyed via
nuclear reactions but not by chemical reactions. Also, there are different kinds of atoms
(differing by their masses) within an element that is known as "isotopes", but isotopes of an
element have the same chemical properties.
Many heretofore unexplained chemical phenomena were quickly explained by Dalton with
his theory. Dalton's theory quickly became the theoretical foundation in chemistry.
J. JOHN THOMSON
Sir Joseph John “J. J.” Thomson (18 December 1856 – 30 August 1940) was a British
physicist and Nobel laureate, credited for the discovery of the electron and of isotopes,
and the invention of the mass spectrometer. Thomson's notion of the electron came from
his work with a nineteenth century scientific curiosity: the cathode ray tube. For years
scientists had known that if an electric current was passed through a vacuum tube, a
stream of glowing material could be seen; however, no one could explain why. Thomson
found that the mysterious glowing stream would bend toward a positively charged
electric plate. Thomson theorized, and was later proven correct, that the stream was in
fact made up of small particles, pieces of atoms that carried a negative charge. These
particles were later named electrons.
MARIE CRUIE
She was born in Warsaw, Poland. Her first name was Maria Skłodowska but generally
known as Madam Curie. She became a student in Sarbone in Faculty of Science. She
graduated from both mathematic and physics departments. In 1894 she met with Pierre
Curie (a physician), and the relationship between them gets deeper. They got married in
1895 and her name changed as Madam Marie Curie.Her daughters Irene and Eve were
born in 1897& 1904.A tragedy happened in 1906, Pierre died in a car accident
In 1896 she began to investigate the gleams that is caused by uranium and named it as
radioactivity. She was the first person use to term ‘radioactivity’. In 1989 she realized that
torium also emits radiations then she decided to investigate all elements in terms of
radioactivity. She concluded that all elements do not have radioactive effects. She
reached the result that:
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Radioactivity is not the interaction between molecules or new shapes of molecules
as in chemical reaction, it must come from the atom itself
HER ACHIEVEMENTS & PRIZES
 In 1903 Nobel Prize in the era of Physics
 In 1906 after her husband’s death she became regions professor in Sorbonne
 In 1908 she became the first female professor in Sorbonne
 In 1911 Nobel Prize in the era of Chemistry
ERNEST RUTHERFORD
Ernest Rutherford was born on August 30, 1871, in New Zealand. His family emigrated
from England before he was born. Ernest left New Zealand for Britain in 1895. He was a
research student at the Cavendish Laboratory under J.J. Thomson, the man who
discovered the electron. He became a professor of physics at McGill University in
Montreal and then at Manchester. In 1919, he was elected Cavendish professor of
experimental physics at the University of Cambridge.
Rutherford's Most Important Work
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In 1906 he moved to the University of Manchester.
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Rutherford teamed up with Hans Geiger, famous for the invention known as the
Geiger counter.
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Together, they set up a centre to study radiation, which was about to change
physics forever.
From the experiment, he was able to deduce that atoms have a central core, which he
called the nucleus and the particles that bounced back directly hit on the nucleus.
Rutherford concluded that an atom must consist of a minute but dense nucleus,
surrounded by space in which electrons orbit. His atomic model's structure, likened into a
planet, became known as Rutherford Planetary Model.
Rutherford concluded that Thomson Atomic Model wasn’t sufficient with the experiment
of bombarding gold foil with alpha particles. According to this model an atom looks like a
tiny planetary system, in which the forces of an electrical attraction operate.
DMITRI MENDELEV
Dmitri Mendeleev (1834-1907)
Born in Siberia, the last of at least 14 children, Dmitri Mendeleev revolutionized our
understanding of the properties of atoms and created a table that probably adorns every
chemistry classroom in the world.
In the late 1860's, Mendeleev began working on his great achievement: the periodic table of
the elements. By arranging all of the 63 elements then known by their atomic weights, he
managed to organize them into groups possessing similar properties. Where a gap existed in
the table, he predicted a new element would one day be found and deduced its properties.
And he was right. Three of those elements were found during his lifetime: gallium, scandium,
and germanium.
Throughout the remainder of his life, Dmitri Mendeleev received numerous awards from
various organizations including the Davy Medal from the Royal Society of England in 1882,
the Copley Medal, the Society's highest award, in 1905, and honorary degrees from
universities around the world. Following his resignation from the University of St.
Petersburg, the Russian government in 1893 appointed him Director of the Bureau of
Weights and Measures. This was believed to have been done to keep down public
disapproval of the government. Mendeleev continued to be a popular social figure until his
death.
NIELS BOHR
He born in Copenhagen on october 7,1885 as the son of Christian Bohr, professor of
physiology at Copenhagen University.His mother came from a family distinguished in the
field of education.In 1903, he entered Copenhagen University He took his master's degree in
Physics in 1909 and his doctor's degree in 1911.He got the award of the Nobel Prize for
1922.
In atomic physics, the Bohr model, devised by Niels Bohr, depicts the atom as a small,
positively charged nucleus surrounded by electrons that travel in circular orbits around the
nucleus—similar in structure to the solar system, but with electrostatic forces providing
attraction, rather than gravity. This was an improvement on the earlier cubic model (1902),
the plum-pudding model (1904), the Saturnian model (1904), and the Rutherford model
(1911). Since the Bohr model is a quantum physics-based modification of the Rutherford
model, many sources combine the two, referring to the Rutherford–Bohr model.
Introduced by Niels Bohr in 1913, the model's key success lay in explaining the Rydberg
formula for the spectral emission lines of atomic hydrogen. While the Rydberg formula had
been known experimentally, it did not gain a theoretical underpinning until the Bohr model
was introduced. Not only did the Bohr model explain the reason for the structure of the
Rydberg formula, it also provided a justification for its empirical results in terms of
fundamental physical constants.
The Bohr model is a primitive model of the hydrogen atom. As a theory, it can be derived as
a first-order approximation of the hydrogen atom using the broader and much more
accurate quantum mechanics, and thus may be considered to be an obsolete scientific
theory. However, because of its simplicity, and its correct results for selected systems (see
below for application), the Bohr model is still commonly taught to introduce students to
quantum mechanics, before moving on to the more accurate but more complex valence
shell atom. A related model was originally proposed by Arthur Erich Haas in 1910, but was
rejected. The quantum theory of the period between Planck's discovery of the quantum
(1900) and the advent of a full-blown quantum mechanics (1925) is often referred to as the
old quantum theory.
ERWIN RUDOLF JOSEF ALEXANDAR SCHRODINGER
In 1887 Schrödinger was born in Vienna, Austria to Rudolf Schrödinger and Georgine Emilia
Brenda (daughter of Alexander Bauer, Professor of Chemistry.His mother was half Austrian
and half English; the English side of her family came from Leamington Spa. Schrödinger
learned English and German almost at the same time due to the fact that both were spoken
in the family household. His father was a Catholic and his mother was a Lutheran.In 1898 he
attended the Akademisches Gymnasium. Between 1906 and 1910 Schrödinger studied in
Vienna under Franz Serafin Exner (1849 - 1926) and Friedrich Hasenöhrl (1874 - 1915). He
also conducted experimental work with K.W.F. Kohlrausch.[1] In 1911, Schrödinger became
an assistant to Exner. At an early age, Schrödinger was strongly influenced by
Schopenhauer[2]. As a result of his extensive reading of Schopenhauer's works, he became
deeply interested throughout his life in color theory, philosophy [3], perception, and eastern
religion, especially Vedanta.
Schrödinger’s Atomic Model
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Electron arrangement around the nuclei of atoms.
The electron is a wave.
An electron can be found in a given region of space at a given time.
This model tells us where the electron might be.
Later, he did the Schöringer’s cat thought experiment to explain it.
Schrödinger's model allowed the electron to occupy three-dimensional space.
The principal (n), angular (l), and magnetic (m) quantum numbers
Each electron shell is made up of a number of subshells.
The number of subshells in a shell is the same as the shell number.
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These subshells can be subdivided into orbitals.
Each orbital is a distinct region.
Each orbital can contain max. 2 electrons.
He generated an equation:
WERNER HEİSENBERG
Werner Heisenberg was born on 5th December, 1901, at Würzburg. He went to the
Maximilian school at Munich until 1920, then he went to the University of Munich to study
physics.From 1924 until 1925 he worked with Niels Bohr, at the University of Copenhagen.
In 1926 he was appointed Lecturer in Theoretical Physics at the University of Copenhagen
under Niels Bohr. In 1927, when he was only 26, he was appointed Professor of Theoretical
Physics at the University of Leipzig.It was in Copenhagen, in 1927, that Heisenberg
developed his uncertainty principle. Heisenberg's name will always be associated with his
theory of quantum mechanics, published in 1925, when he was only 23 years old. For this
theory and the applications of it which resulted especially in the discovery of allotropic forms
of hydrogen, Heisenberg was awarded the Nobel Prize for Physics for 1932. His new theory
was based only on what can be observed, that is to say, on the radiation emitted by the
atom. We cannot, he said, always assign to an electron a position in space at a given time,
nor follow it in its orbit, so that we cannot assume that the planetary orbits postulated by
Niels Bohr actually exist.
Mechanical quantities, such as position, velocity, etc. should be represented, not by ordinary
numbers, but by abstract mathematical structures called "matrices" and he formulated his
new theory in terms of matrix equations.
Uncertainty Principle:
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states that certain pairs of physical properties, like position and momentum, cannot
both be known to arbitrary precision.
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That is, the more precisely one property is known, the less precisely the other can be
known.
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According to Heisenberg its meaning is that it is impossible to determine
simultaneously both the position and velocity of an electron or any other particle
with any degree of accuracy or certainty.