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Period: 460 BCE to 370 BCE
Democritus
Democritus. Democritus, c.460-c.370 BC, a Greek philosopher, developed and systematized classical atomism, a theory credited to his teacher Leucippus. The theory postulated a world made up of hard, indivisible (hence atomic, from Greek atoma, "uncuttable") particles of matter moving through empty space.O -
Period: 384 BCE to 322 BCE
Aristotle
is theory gives birth to the atom. Aristotle, practical as ever in his determination to get things worked out in detail, proposes a new theory to explain how the four elements of Empedocles and the atoms of Democritus produce the wide range of substances apprehended by our senses. -
Period: 300 BCE to 500 BCE
Alchemy part 1
332 BC Alexander the Great had conquered Egypt
Greek philosophers became interested in the Egyptian religion. Greek views of how matter is made up of the four elements of nature were merged with Egyptian religion.
The result was Khemia, the Greek word for Egypt.
The word Alchemy came from the word Khemia, which means Egypt. -
Period: 600 to 700
Alchemy part 2
Arabs occupied Egypt and further developed the science, spread it to the West (Spain) in 700s.
Metals are made up of mercury and sulfur in varying proportions.
Gold is the perfect metal and all others were “Baser” metals, capable of being transmuted into gold by means of a substance known as the Philosophers Stone.
Alchemists applied this concept of purification and search for
perfection to the human condition, and sought spiritual purification
and immortality -
Period: 1500 to
Alchemy part 3
the alchemists in Europe had separated into two groups:
western alchemists focused on the discovery of new
compounds, reactions, and chemical processes - leading to what is now the science of chemistry. Invented Distillation, percolation, extraction, rudimentary chromatography.
The second group continued to look at the more spiritual,
metaphysical side of alchemy, continuing the search for
immortality and the transmutation of base metals into gold. This
led to the modern day idea of alchemy. -
Period: to
Vitalism
Living organisms are fundamentally different from non-living entities because they contain a “vital spirit”. Living things are thus governed by different principles than are
inanimate things. -
Period: to
The Phlogiston Theory
from the Ancient Greek phlogistón "burning up"
first stated in 1667 by Johann Joachim Becher
postulated the existence of a fire-like element called "phlogiston",
which was contained within combustible bodies and released
during combustion.
A substance that burned did so because it contained Phlogiston.
Carbon Dioxide, no longer capable of burning was called
“dephlogisticated air” -
Period: to
Anton Lavoisier
Lavoisier disproved the phlogiston theory. He demonstrated that there was an element called oxygen that played a major role in combustion. Proved no mass is lost in a chemical reaction This became known as the Law of Conservation of Mass and is one of the most important and basic laws of modern chemistry and physics. He created a system to name chemical compounds, proved water was not an element. 1789, Lavoisier wrote the Elementary Treatise of Chemistry it was the first book on chemistry -
Benjamin Franklin
idea was that hot gases which would normally simply go up the flue would exchange their heat with cold air from the room, heating it up, and so heating the room up.Franklin was the first to write that electric charge cannot be created; it can only be ‘collected. fundamental laws of physics – the Law of Conservation of Electric Charge. It means that you cannot create(or destroy)electric charge. Storms don’t travel in the direction of prevailing wind.important scientific discipline of meteorology. -
Joseph Louis Proust
The law of definite composition was proposed by Joseph Proust based on his observations on the composition of chemical compounds. Proust proposed that a compound is always composed of the same proportions of elements by mass.law of constant composition says that, in any particular chemical compound, all samples of that compound will be made up of the same elements in the same proportion or ratio. Ex; any water molecule is always made up of two hydrogen atoms and one oxygen atom in a 2:1 ratio -
Period: to
John dalton
was an English chemist, physicist, and meteorologist. He is best known for proposing the modern atomic theory and for his research into colour blindness, sometimes referred to as Daltonism in his honour. -
Period: to
William crookes et. Al.
A. Cathode Ray Tube (CRT)
CRT – a glass tube th18at is evacuated (contains no air or matter) coated with fluorescent paint. When connected to a battery, the paint glows, indicating that there is some type of radiation streaming from the battery (the cathode).
B. Paddle wheel placed in CRT:
When Crookes placed a paddle wheel in the CRT and turned on the battery, the wheel spun. Since the tube was evacuated, this told Crookes that the Cathode Ray has mass. -
Sir John Joseph Thomson
His work also led to the invention of the mass spectrograph. The British physicist Joseph John (J. J.) Thomson (1856–1940) performed a series of experiments in 1897 designed to study the nature of electric discharge in a high-vacuum cathode-ray tube, an area being investigated by many scientists at the time -
Period: to
Ernest Rutherford Part 1
A. Classification of radiation
B. Famous Gold Foil Experiment
1. What he did:
Stretched a sheet of gold foil in a tin can and coated the inside of the can with fluorescent paint.
Aimed a ray of alpha radiation (+ charges) at the foil.
Expected that the alpha rays would pass right through the metal atoms in the foil, and the fluorescent coating would light up right behind the foil. -
Becquerel
The Discovery of Radioactivity. In 1896 Henri Becquerel was using naturally fluorescent minerals to study the properties of x-rays, which had been discovered in 1895 by Wilhelm Roentgen.Henri Becquerel discovers radioactivity on February 26, 1896. Credit: A photographic plate made by Henri Becquerel shows the effects of exposure to radioactivity. A metal Maltese cross, placed between the plate and radioactive uranium salt, left a clearly visible shadow on the plate -
Curies (Marie and Pierre)
In 1911 she was awarded the Nobel Prize in Chemistry. The citation by the Nobel Committee was, "in recognition of her services to the advancement of chemistry by the discovery of the elements radium and polonium, by the isolation of radium and the study of the nature and compounds of this remarkable element -
Period: to
Ernest Rutherford - Part 2
Many of Rutherford’s discoveries also became the basis of the European Organization for Nuclear Research’s construction of the Large Hadron Collider. The largest and highest-energy particle accelerator in the world and decades in the making. It has since been used to answer fundamental questions about physics, by scientists who share in Rutherford’s tendency toward forward-thinking and his relentless quest for proof through scientific exploration -
Robert Millikan
1909 Millikan began a series of experiments to determine the electric charge carried by a single electron. He began by measuring the course of charged water droplets in an electric field. The results suggested that the charge on the droplets is a multiple of the elementary electric charge, but the experiment was not accurate enough to be convincing. He obtained more precise results in 1910 with his famous oil-drop experiment in which he replaced water (which evaporated too quickly) with oil. -
James Chadwick
James Chadwick played a vital role in the atomic theory, as he discovered the Neutron in atoms. Neutrons are located in the center of an atom, in the nucleus along with the protons. They have neither a positive nor negative charge, but contribute the the atomic weight with the same effect as a proton.In 1935, James Chadwick received the Nobel Prize in Physics for his discovery of the neutron.A neutron collides with an atom of nitrogen-14. The nitrogen atom splits into boron-11 and helium-4