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History of Chemistry
Teresa Galloway
JFKS
If I have seen further it is by standing on the shoulders of giants.
Sir Isaac Newton
Chemistry through the Years- 18th Century: Gas
Chemistry
- 19th Century: Organic Chemistry
- 20th Century: Nuclear Chemistry
- 21st Century: Quantum Chemistry
More on the Periodic Table:
• Daniel Radcliffe sings the Element Song
Historical Outline of Atomic Theory Website
• History Website
• Corrosion Doctors Website
Greek View
Democritus: 470-380 BCCoined the term “atom”
Aristotle: 384-322 BCFour Element Concept
Ancient Philosophers
21 Centuries Later………..
• Robert Boyle: (1627-1691 Ireland)
• In 1665 in Oxford, along with his assistant Robert Hooke devised the vacuum chamber
• First prominent scientist to perform controlled experiments and publish his work
• Boyles Law: P1V1 = P2V2
Antoine Lavoisier (1743-1794 France)
• First person to make good use of the balance changing chemistry from qualitative to quantitative
• Disproved Phlogiston Theory/instead proposed Combustion Theory
• Law of Conservation of Mass
• Beheaded by guillotine in 1794
• Antoine Lavoisier YouTubeVideo
Joseph Proust (1754-1826 France)
• Law of Constant Proportions 1799– The proportions of the components of a
chemical compound are always the same no matter how it is prepared
– became more clear to scientists in 1803 with the help of John Dalton
– FYI: First to identify the sugar that comes from grapes as glucose
Amadeo Avogadro (1776-1856 Italy)
• Avogadro’s Hypothesis: 1811
• At the same temperature and pressure, equal volumes of gases contain the same number of molecules
• Extremely radical for the time period, was not accepted for another 50 years (Karlsruhe Conference 1860)
A Mole is a Unit
John Dalton (1766-1844 England)
• Daltons Atomic Theory: (1803)• Elements are made of tiny particles called atoms• All atoms of the same element are identical
(later to be revised)• The atoms of a given element are different from
those of any other element• Elements combine to form compounds• Mass is neither created or destroyed in a
chemical reaction, but can be rearranged.
Events Leading to the Periodic Table:
• Johann Dobereiner (1817)
• Law of Triads
• Proposed that nature contains triads of elements where the middle element has properties that were an average of the other two members when ordered by the atomic weight (Li,Na,K)
John Newlands (1863 England)
• Law of Octaves
• Any given element will exhibit analogous
behavior to the 8th element following it in the periodic table.
Dmitri Mendeleev (1834-1907 Russia)
• Late 1860’s, arranged the 63 known elements (known by atomic weights) into groups based on chemical and physical properties
• Where a gap existed, he predicted a new element would be found and its properties, Ga (1875), Sc (1879), Ge (1886) were found during his lifetime
• YouTubeVideo on Mendeleev
Lothar Meyer
• Meyer’s 1864 textbook included an abbreviated version of the periodic table consisting of appx ½ of the elements listed in order by atomic weight and demonstrated periodic valence changes as a function of atomic weight.
• In 1868 he constructed an extended table and gave it to a colleague to evaluate
Meyer vs Mendeleev
http://www.chemheritage.org/discover/chemistry-in-history/themes/the-path-to-the-periodic-table/meyer-and-mendeleev.aspx
Discovery of the Noble Gases
• 1904 Chemistry Nobel Prize for Ramsey and physics for Rayleigh
• Lord Rayleigh was studying nitrogen in the air and noted that the weight was always greater than that of N2 in other compounds thus Argon was found.
• Discovery of the other noble gases then quickly followed
Glenn Seaborg
• Starting with his discovery of plutonium in 1940, he discovered all the transuranium elements (94-102)
• He reconfigured the periodic table by placing the actinide series below the lanthanide series
• 1951 received Nobel Prize in chemistry for his work
• Glenn Seaborg and the discovery of 10 elements
J.J. ThomsonBritish 1856-1940
• Nobel Prize in physics 1906
• 1871 became a professor at the Cavendish Laboratories in Cambridge England
• Experimented with electrical currents inside empty glass tubes (cathode rays)
• Bold proposal that these mysterious rays are streams of particles much smaller than atoms
• Proposed the first model of the atom with subatomic particles
• Credited with the discovery of the electron based from his work with cathode ray tubes
• Plum Pudding Model: the atom is made up of a positively charged pudding with negative electrons distributed throughout to neutralize the atom
• cathode ray tube
• Sir JJ Thomson
Robert Millikan Oil Drop Experiment
• Performed in 1909 determined the size of the charge of an electron
• Oil Drop Experiment
Ernest Rutherford
• New Zealand, 1871-1937, physicist
• Awarded a scholarship to Cambridge University (1894) where he was influenced by JJ Thomson to study the recently discovered x-rays
• Coined the terms: alpha, beta and gamma rays, half-life, proton
• Given credit for the proton, and nucleus
• 1907 went to Univ. of Manchester to work with Hans Geiger
• 1908 received Nobel Prize in chemistry for his work with radiation and the atomic nucleus
• Appx1909 discovered the atomic nucleus and proposed a model of the atom
• Gold Foil Experiment (1909)-the atom is mainly empty space through which electrons move and there is a tiny dense region “nucleus” centrally located that contained all of an atom’s positive charge
• Rutherfords Gold Foil Experiment
• Another Look at Gold Foil
H G J Moseley
• Died at the age of 27, shot through the head by a Turkish bullet at Gallipoli in 1915.
• “ein schwerer Verlust für die Naturwissenschaften”
• Studied the frequency of x-rays given off by cathode ray tubes when electrons strike the anode.
• Found that there was a relationship between the frequencies (v) of the x-rays given off by the cathode ray tube and the atomic number of the metal used to form the anode.
• Conclusion: The atomic number was equal to the positive charge (charge on the nucleus) of an atom. (1914)
• This then caused the periodic table to be reorganized based on atomic number of the element, not atomic weight.
James Chadwick1891-1974, British
• 1911 spent two years working with Ernest Rutherford
• Main studies were with radioactivity
• Along with Rutherford and others noticed that the proton did not account for all the mass of an atom, that the atomic mass was always more than the atomic number
• Hypothesis of the time was that there was a proton-electron pairing in the nucleus making up for the difference of the mass
• Influenced by the work of Frederick and Marie –Joliot Curie and their work with radiation
• 1932 neutron discovered to be the “neutral” particle that weighed 0.1% more than the proton accounting for the mass
• 1935 Nobel Prize for his work
• Bill Nye the Science Guy: Atoms
Neils Bohr
• Quantum Mechanics The Structure of Atoms
Niels Bohr 1885-1962, Danish
• 1922 Nobel Prize in physics for his work on the atomic structure
• Studied under Rutherford in Manchester
• Expanded Rutherfords theory that electrons could travel in certain orbits and that the outer orbits determined the chemical properties of the atom
• Also described the way atoms emit radiation by suggesting that if an electron gains energy it can jump from ground state to a higher energy level “excited” state. And when the electron loses energy and falls back to a lower energy level, it gives off a photon of light.
• 1939 visited the USA and relaid news that German scientists were working on splitting the atom, which spurred the creation of the Manhattan Project
Werner Heisenberg 1901-1976, German Physicist
• Influenced by the work of James Chadwick
• 1927 Uncertainty Principle: It is impossible to know both the exact location & velocity of an electron at any given time.
• Nobel Prize in Physics in 1932 for the creation of quantum mechanics, the application which has led among other things to the discovery of the allotropic forms of hydrogen
Ich bin Werner Heisenberg
Quantum Mechanics
Where are we today?
