-
3750 BCE
Carbon
-Discovered by Joseph Black
-Fourth most abundant substance
-Present in all living organisms -
3000 BCE
Gold
-One of the first elements discovered
-Element 79
-It's symbol is Au.
-Used for coinage and has been used as standard for monetary systems in some countries.
-Unreactive -
Period: 460 BCE to 370 BCE
Democritus
-formulated the earliest model of Atomic Theory.
-was an Ancient Greek pre-Socratic philosopher
-theorized that all material bodies are made up of indivisibly small “atoms.” -
Period: 384 BCE to 322 BCE
Aristotle
His refutation of Democritus' Atomic theory led to years of bogus "science". He believed in four elements:Earth, Air, Fire, and Water -
Period: 300 BCE to 500
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 Philosopher's 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 looked 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. -
Robert Boyle
-Studied the behavior of gases and discovered the inverse relationship between volume and pressure of a gas.
-Stated that “all reality and change can be described in terms of elementary particles and their motion,” an early understanding of atomic theory.
-He wrote the first chemistry textbook, “The Sceptical Chemist,” in 1661 which moved the study of substances away from mystical associations with alchemy and toward scientific investigation -
Phosphorous
-The first scientific discovery of an element
-Discovered by Hennig Brand
-The symbol is P
-The atomic number is 15.
-Essential for life. -
Period: to
The Phlogiston Theory
From the Ancient Greek phlogistón "burning up"
first stated in 1667 by Johann Joachim Becher.The belief of 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” -
Isaac Newton
-Developed the three laws of motion which form the basic principles of modern physics.
-He discovered calculus which led the way to more powerful methods of solving mathematical problems.
-Theorized a mechanical universe with small, solid masses in motion. -
Joseph Priestley
-Disproved of the idea that air was an indivisible element.
-Showed that it was, instead, a combination of gases when he isolated oxygen and went on to discover seven other discreet gases. -
Jacques Charles
-Continued Boyles’ work
-Known for stating the direct relationship between temperature and pressure of gases. -
Period: to
Anton La Voisier
-Father of Modern Chemistry because he relied on quantitative
observation to develop conclusions.
-Dispelled the Phlogiston Theory by proving that Oxygen causes
combustion.
-Discovered the Law of Conservation of Mass: By proving that the
mass of a metal oxide = the mass of the metal plus oxygen when
the metal oxide decomposes.
-Matter can change form, but cannot be created nor destroyed
in a chemical reaction.
-Beheaded during French Revolution -
Benjamin Franklin
Discovered that electrical charges come in 2 varieties – positive and
negative. Like charges repel, opposite charges attract. -
Joseph Louis Proust
-Studied pure chemical compounds and stated the Law of Definite Proportions
- a chemical compound will always have its own characteristic ratio of elemental components. Water, for instance, always has a two-to-one ratio of hydrogen to oxygen -
Hydrogen
- Discovered by Henry Cavendish -It's a colourless, odourless gas. -Essential element for life.
-
Period: to
John Dalton - Father of Atomic Theory
Dalton’s Atomic Theory of Matter:
A. Matter is made up of atoms that are indivisible and indestructible.
B. All atoms of an element are identical. (Known now to be untrue!)
C. Atoms of different elements have different weights and different
chemical properties.
D. Atoms of different elements combine in simple whole numbers to form compounds.
E. Atoms cannot be created or destroyed. When a compound
decomposes, the atoms are recovered unchanged. -
Amedeo Avogadro
-Clarified the difference between atoms and molecules.
-Stated that equal volumes of gas at the same temperature and pressure have the same number of molecules.
-The number of molecules in a 1-gram molecular weight (1 mole) sample of a pure substance is called Avogadro’s Constant in his honor.
-It has been experimentally determined to be 6.023 x 1023 molecules
-It is an important conversion factor used to determine the mass of reactants and products in chemical reactions. -
Humphrey Davy
-known for the discovery for earth based alkaline metals and alkali
-discovered the nature of chlorine and iodine in its natural state. In addition, people remember for his identifying earth based alkaline metals and alkali itself -
Antoine Lavoisier
-Discovered the Law of Conservation of Mass.
-Published "Methods of Chemical Nomenclature," which included the rules for naming chemical compounds that are still in use today.
-Clearly defined a chemical element as a substance that cannot be reduced in weight by a chemical reaction and listed oxygen, iron, carbon, sulfur and nearly 30 other elements then known to exist. -
Michael Faraday
-known for his contributions in electrochemistry and electromagnetism
-studied chlorine and carbon
-the first to identify would known as nanoparticles in mettalic form.
-created the earliest type of Bunsen burner -
Beryllium
-founded by Louis Nicolas Vauquelin
-highly toxic
-ingestible
-carcinogenic -
Boron
- vital for life
- present in borates
- discovered by Joseph-Louis Gay-Lussac and Louis-Jaques Thénard, Fr
-
Johann Dobereiner
-Noticed that the atomic weight of strontium fell midway between the weights of calcium and barium, elements possessing similar chemical properties.
-Discovered the halogen triad composed of chlorine, bromine, and iodine and the alkali metal triad of lithium, sodium and potassium
-Proposed that nature contained triads of elements the middle element had properties that were an average of the other two members when ordered by the atomic weight (the Law of Triads). -
Lithium
-Discovered by Johan August Arfvedson
-Toxic
-It's a soft, silvery metal -
Louis Pasteur
-known for the process of Pasteurization
-creator of Vaccines for Rabies and Anthrax
-developed the process of Pasteurization
-discovered the as-symmetrical molecular structure on certain crystals.
-created the reduction of a bacterial infection in what is known as puerperal fever. -
Dmitri Mendeleev
Came up with the first design or drawing of the Periodic Table of Elements -
Period: to
William Crookes et. al.
A. Cathode Ray Tube (CRT)
CRT – a glass tube that 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. -
John Newlands
-Wrote a paper which classified the 56 established elements into 11 groups based on similar physical properties
-In 1864, published his version of the periodic table and proposed the Law of Octaves (by analogy with the seven intervals of the musical scale).
-This law stated that any given element will exhibit analogous behavior to the eighth element following it in the table -
Otto Hahn
- “Father of Nuclear Chemistry” -one of the earliest men to work in the field of radiochemistry and radioactivity. Xfounded what is known as “Applied Radiochemistry” which eventually led to nuclear chemistry
-
Erwin Schrodinger
-Developed mathematical equations that describes the motion of an atom.
-He received the Nobel Prize for his work.
-His work also leads to an electron cloud model.
-Erwin believed that an electron's path does not go in a exact path.
-Erwin's model was a nucleus{which had positively charged protons}surrounded by a electron cloud where the electron orbit. He believed where ever more dense the more likely the electron will be there -
Ernest Marsden
He did a "gold foil experiment." to determine the direction of alpha particles. -
George Johnstone Stoney
He wrote a letter titled Of the “Electron”, or Atom of Electricity to the editors of the Philosophical magazine. He calls a definite quantity of electricity E¬r which is later developed to be an ‘electron’. Also, he estimates the mass of an electron. We know the mass on an electron and that it is a definite quantity of electricity -
Discovery of the Noble Gases
-Lord Rayleigh reported the discovery of a new gaseous element named argon which proved to be chemically inert.
-William Ramsey suggested that argon be placed into the periodic table between chlorine and potassium in a family with helium, despite the fact that argon's atomic weight was greater than that of potassium.
-This group was termed the "zero" group due to the zero valency of the elements.
-Ramsey accurately predicted the future discovery and properties neon. -
Helium
- Discovered by Sir William Ramsay -It's a colourless, odourless gas that is totally unreactive. -Not essential to life
-
Electron Cloud Model
-The electron cloud model is an atom model wherein electrons are no longer depicted as particles moving around the nucleus in a fixed orbit.
-The electron cloud model describes their probable location around the nucleus.
-The model doesn’t show us the exact location of the electrons around the nucleus. -
Sir John Joseph Thomson
A. Continued experimenting on the CRT:
-JJ Thomson used charged plates to deflect the cathode ray.
- Found the ray deflected away from the negative plate, and toward the positive.
B. Deduced that the cathode ray was made of: Negative particles that he named electrons -
Max Planck
-He developed the Quantum theory.
-He attempted to draw conclusions from the heat radiation to the radiating atom.
-The discovery of quanta changed the idea of physics, because it showed that established ideas about the nature of radiation and energy were wrong. -
Period: to
Ernest Rutherford
A. Classification of radiation
B. Famous Gold Foil Experiment
- 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. -
Linus Pauling
-known for his work in molecular biology and quantum chemistry
-received the Nobel Prize in his field of chemistry in 1954. -
Becquerel
Discovered radioactivity in Uranium ore. -
Curies (Marie and Pierre)
-Discovered and isolated polonium and radium from uranium ores.
-The study of radioactive elements (elements that spontaneously change into different elements due to instability) gave scientists the inkling that there had to be something inside the atom that gave it its identity, and that if that thing changed, the atom would change or “transmute” into another element. -
Hantaro Nagaoka
-He was the first scientist to present a Saturnian model of an atom.
-The model displayed a nucleus containing positive electric charge and electrons ‘orbiting’ it. It gave us an idea of what an atom looked like, making it easier to understand the structure of it -
Albert Einstein
-Einstein devised a mathematical method of calculating the size of atoms and molecules.
-The paper Einstein wrote didn’t say much more about the waves of frequency and the relation to an atoms particles. -
Milikan
Calculated the mass and charge of an electron. -
Henry Gwyn Jefferys Moseley
-He found a relationship between an element’s X-ray length and its atomic number.
- Before he discovered this, the atomic numbers were just sequential numbers based on the element’s atomic weight. It showed that there was a gap between atomic numbers 43 and 61 in the table. It shows that the atomic numbers of the elements aren’t just numbers based on the element’s weight but has connection with the element’s X-ray length. -
Rosalind Franklin
-known for the discovery of the DNA structure in genetics
-her contributions to science involve the study of the structures of coal, graphite, DNA, RNA, and viruses in understing their molecular structures -
Niels Henrik David Bohr
-Awarded the Nobel Prize in physics
- Bohr explained what happens inside an atom and developed a picture of atomic structure. Bohr was also the first to discover that electrons travel in separate orbits around the nucleus and that the number of electrons in the outer orbit determines the properties of an element. The Bohr model however provides an incorrect value for the ground state orbital angular momentum. -
Werner Heisenberg
Gamma Rays:
- Believed you couldn't actually observe the electrons move in a circle.
- He used quantum physics and math to prove that electrons orbit a proton filled nucleus but those electrons didn't orbit in a circle.
-Werner conducted an experiment with gamma rays and tried to observe the electron, but every time he tried to observe the electron with a high powered microscope it only got faster.
-Werner Heisenberg wins a Nobel Prize in Physics -
Louis de Broglie
-Broglie discovered that electrons can act like waves which helps explain some of the things electrons do that we had never been able to explain before.
-Broglie questions, could you locate the precise position of the electron within the wave?
-German scientist Heisenberg proved this to be incorrect. -
James Chadwick
Proved the existence of another subatomic particle, that had no charge, named it the neutron. -
Hideki Yukawa
- Had a theory of mesons ( hadronic subatomic particles ). -The theory explained the interaction of neutrons and protons.
- In 1936 his theory was proved because Carl David Anderson & others observed charged pi mesons. -The mechanisms of nuclear binding and decay became problems in the theory, but it was proved after the observation(s).
