Transcript Chemistry for Changing Times 11th Edition Hill and Kolb
Chemistry for Changing Times
12 th Edition Hill and Kolb
Chapter 2 Atoms: Are They for Real?
John Singer Jackson Community College, Jackson, MI © 2010 Pearson Prentice Hall Inc.
Atoms: The Greek Idea
~384 B.C.E., Aristotle
: All matter is composed of four elements and all matter is continuous, not atomistic.
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Atoms: The Greek Idea
~ 450 B.C.E., Leucippus and Democritus
Atomos
: The point at which matter can no longer be subdivided.
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Atoms: The Greek Idea
Aristotle
declared matter to be
infinitely divisible
.
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Lavoisier: The Law of Conservation of Mass
Early 1700s Lavoisier:
Law of Conservation of Mass:
During a chemical change, matter is neither created nor destroyed.
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Lavoisier: The Law of Conservation of Mass © 2010 Pearson Prentice Hall, Inc.
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Proust: The Law of Definite Proportions
1799, Proust: Law of Definite Proportions:
A compound always contains the same elements in certain definite proportions.
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Proust: The Law of Definite Proportions Regardless of the source, copper carbonate has the same composition.
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Proust: The Law of Definite Proportions The Berzelius experiment illustrates the Law of Definite Proportions.
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John Dalton and the Atomic Theory of Matter
1803, John Dalton:
Law of Multiple
Proportions:
Elements may combine in more than one set of proportions, with each set corresponding to a different compound.
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John Dalton and the Atomic Theory of Matter © 2010 Pearson Prentice Hall, Inc.
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John Dalton and the Atomic Theory of Matter • All matter is composed of extremely small particles called
atoms
.
• All atoms of a given element are alike and differ from the atoms of any other element.
• Compounds are formed when atoms of different elements combine in fixed proportions.
• A chemical reaction involves the rearrangement of atoms. © 2010 Pearson Prentice Hall, Inc.
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Out of Chaos: The Periodic Table
1869, Dmitri Mendeleev
Mendeleev arranged the elements in order of increasing atomic mass. He left gaps for yet undiscovered elements. He also predicted the properties of those elements. When those elements were eventually discovered, many of his predictions were found to be accurate.
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Out of Chaos: The Periodic Table © 2010 Pearson Prentice Hall, Inc.
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Out of Chaos: The Periodic Table © 2010 Pearson Prentice Hall, Inc.
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Atoms: Real and Relevant Atoms are a very real concept. It is even possible to observe computer-enhanced images of atoms.
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Leucippus Revisited: Molecules
Molecules
are groups of atoms chemically bonded together. A molecule of water is composed of two atoms of hydrogen (H) bonded to an atom of oxygen (O). H 2 O © 2010 Pearson Prentice Hall, Inc.
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