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| Carl Sagan's COSMOS is one of the most influential science programs ever made.
Q. Does the moon have a dark side?
A. The moon does have a far side which is impossible to see from the earth, but it doesn't mean that it's always dark. Each side of the moon is dark for no longer than 15 days at a time.
Q. Where does sound come from?
A. The air is always filled with sound waves. All things give off vibrations, but some have a low frequency which most cannot hear. The reason: it may take 3 minutes to make a single vibration. They may be caused by earthquakes and storms.
Did You Know?
The microwave was invented after a researcher walked by a radar tube and a chocolate bar melted in his pocket.
Coke-a-Cola was originally green.
Rubberbands last longer when refrigerated.
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Dalton, John: 1766-1844
by Jeanette Cain
John Dalton was the originator of atomic theory, which theory provided scientists with new ways of seeing the physical world. Atomic weights and fixed
ratios of atoms inside compounds provided researchers with the knowledge to explore chemical compositions of matter.
Dalton's new information on atomic weights allowed a Russian chemist, Dmitry Mendeleyev, to create the periodic table of elements. This table provided the means for discovering new elements, and
Dalton also proposed symbols for the elements. The symbols would represent the atom combination in compounds, but these were later changed to the abbreviations known today. Dalton's theory had
been accepted at the time, but it opened new questions about atom interactions. The structure and interaction of atoms refined atomic theory.
Until Dalton, the lines between physics and chemistry was almost unnoticeable, but his atomic theory distinguished and divided the two disciplines. In physics and chemistry, the atom is a
cornerstone providing an understanding of matter and force, especially in quantitative analysis. Quantitative analysis refers to the measurement of "how much" of a certain substance is within a
sample. Dalton's theory was the beginning of nuclear energy and fusion research still used today.
The theory also provides for the study of the quantitative relationships between substances in chemical reactions, or stoichiometry. It provides for structural theory and arrangements of atoms
for influencing properties. Dalton's models eventually turned into the understanding of 3-dimensional qualities of molecules and the affect of structure on properties. Dalton's theory did have
some inaccuracies, but it did provide the foundation for future generations of scientists.
John Dalton was born in Eaglesfield, England, on September 6, 1766 into a Quaker family. Dalton attended school until the age of twelve, when he became a teacher and taught for the rest of his
life. In 1794, Dalton published a scientific paper on color-blindness, from which he suffered. Because of Dalton's research, color-blindness is called Daltonism.
Dalton became interested in the natural sciences when a friend introduced him to meteorology. In 1787, Dalton started daily recordings of weather observations. His observations came to have over
200,000 items, as Dalton pondered over the atmosphere and its make-up. In 1803 Dalton published his law of partial pressures known as Dalton's Law. Dalton's Law says that when different
gases combine, the resulting pressure will be the sum of what each gas gives individually.
Dalton's studies led to the conclusion that gases had to be made of small particles. Taking and increasing Democritus' idea that atoms could not be split, Dalton created the new atomic theory.
Dalton said that all matter is made of small and indivisible parts, that they are not capable of being destroyed and that they could not be changed. Dalton also said that each element had a
different type of atom, that is, that all gold atoms are alike to one another, but different from the other elements. He also said that each has a weight capable of being measured.
In 1808, Dalton published New System of Chemical Philosophy, which was a list of weights for specific elements. In 1826, Dalton received a Royal Medal for this work. Dalton supported
himself by teaching, and in his later years, scientific research was put aside to provide income from teaching. John Dalton died at his English home on July 27, 1844.
Sources:
1. Asimov, Isaac. A Short History of Chemistry. Westport, CT.: Greenwood Press, 1965.
2. Editors. The World Book Encyclopedia. World Book-Childcraft International, Inc: Chicago. 1990
Further Study:
John Dalton
Narrative tale by John Dalton's brother.
No. 1411: John Dalton's Notation
Presented by The University of Houston's College of Engineering. Series about machines and the people creating them.
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