History: On the Human Side

1. John Dalton(1766 - 1844) Dalton's early career was the study of mathematics and Newtonian theories of gravity and forces. In addition, he compiled meteorological records and constructed barometers, thermometers, rain gauges and hygrometers. His research on gases led to the formulation that in a mixture of gases each gas acts as an independent entity (law of partial pressures). Dalton was the first scientist to explain that air is a mixture of gases and not a vast "chemical solvent," as many chemists had been theorizing based on their observations of evaporation and boiling of substances. Between 1805 and 1807 Dalton began shifting his interests increasingly towards chemistry. During a series of lectures in Edinburgh, he described a new system of examining chemical combinations. In 1807 he described atoms as the indivisible particles of matter that bonded together by hooking to form all the compounds present in nature. He envisioned this hooking to be similar to fish hooks that would latch onto one another. For this and other theories, Dalton was later elected to the Royal Society. He was also instrumental in the founding of the British Association for the Advancement of Science.

2. Edward Frankland(1825 - 1899) Frankland developed a theory of valence following research into the properties of zinc methyl, a new reactive organometallic compound, and a series of alkyl-conjugated metals which had different combining powers than the metals alone. On May 10, 1852, Frankland published an article describing the fixed combining powers of elements which he termed `atomicity.' This term was renamed valence. Frankland's work on valence, along with an international agreement on atomic weight values signed shortly thereafter united various theoretical schools of chemists into the field of structural chemistry.

3. Archibald Scott Couper(1831 - 1892) In 1856, Couper began research on the bromination of benzene at the laboratory of Charles Wurtz in Paris. He asked Wurtz to present a paper which he had written titled "On a New Chemical Theory" to the French Academy of Sciences. However, before his paper was presented a similar paper was presented by Friedrich Kekule. By the time Couper's paper was read, Kekule had claimed priority for the formulas for bromobenzene (B6H5Br) and p-dibromobenzene (C6H4Br2). Couper, after complaining to Wurtz about the delay in presenting his paper, was dismissed from the lab and returned to his native Scotland. His subsequent research on carbon showed that it has a valence, or combining power, of two or four, forms valence links with other carbon atoms, and thereby forms carbon chains. Couper represented these links with lines and in 1858 introduced the first "ring formula" to organic chemistry.

4. Linus Pauling(1902 - ) Pauling began his studies as an undergraduate at Oregon State Agricultural College. In order to pay for his classes, he taught quantitative analysis and offered tutorials on freshman chemistry. by 1920, when he was a senior, Pauling was offering a seminar on the electronic nature of the chemical bond. He based this course on Lewis and Langmuir's theories of chemical bonding published in 1916. Pauling attended the California Institute of Technology beginning in 1922. At the time Caltech was one of the first institutions using the new methods of X-ray crystallography to analyze structures, and while still a graduate student, Pauling published seven papers on crystal structures. By 1928, after studying in Europe for a year, Pauling was doing frontier research on chemical bonding. Beginning in 1931 he published a seven-part series titled "The Nature of the Chemical Bond." New rules for determining bond lengths, the angles between bonds, magnetic moments and other molecular properties were described using the concept of resonance. Pauling's theory held that molecules can be represented by a linear combination of wave functions. He thus transformed the field of chemistry by applying quantum theory and quantum mechanics to chemical structure and bonding. Pauling has continued to study molecular structure with emphasis on the structure of protein molecules from living tissue. Through his success in determining protein structures, Pauling established himself as a founder of modern molecular biology.

   In 1954, Pauling received the Nobel Prize for his research into the nature of the chemical bond. In addition to his scientific work he has been an outspoken advocate of peaceful resolution of conflict. Such activities resulted in his receipt of a second Nobel Prize, the Peace Prize, in 1963.

5. G.N. Lewis made significant contributions to ideas about the chemical bond. A brief biography is in Masterson, W. L., and Hurley, C. N. (1989).Chemistry: Principles and reactions (pp. 272-273). New York, NY: Saunders.

	TABLE OF CONTENTS	TOPIC OVERVIEW	CONCEPT/SKILLS DEVELOPMENT	LINKS/CONNECTIONS	EXTENSIONS