lecture%207%20%28chapt5%29 - Chapter 5 Exam is not graded...

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1 Chapter 5 Exam is not graded yet- I hope to hand them back on Wed One of the main quests of science throughout the ages has been to discover what matter is made of - and what holds it together.
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2 Democritus Greek Philosopher About 450 B.C All matter is composed of tiny indivisible particles. Named these particles atomos meaning “indivisible” Aristotle Greek Philosopher About same time as Democritus Disagreed with Democritus Did not believe in atoms 4 elements: Earth Air Water Fire John Dalton 1803 Dalton’s Atomic Theory of Matter: Each element is composed of extremely small particles called atoms All atoms of a given element are identical, but they differ from those of any other element. Atoms are neither created nor destroyed. A given compound always has the same relative numbers and kinds of atoms. Dalton’s Model of the Atom : Billiard Ball Model: the same throughout An An atom atom is the is the smallest and simplest smallest and simplest unit into which an element can be divided while which an element can be divided while maintaining the properties of the element. maintaining the properties of the element.
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3 Take a pile of paper clips (all of the same size and color). Divide the pile into two equal piles. Divide each of the smaller piles into two equal piles. Repeat step 3 until you are down to a pile containing only one paper clip. That one paper clip still does the job of a paper clip (i.e., hold loose papers together). Now, take a pair of scissors and cut that one paper clip in half. Can half of the paper clip do the same job as the single paper clip? If you do the same thing with any element, you will reach an indivisible part that has the same properties of the element, like the single paper clip Paperclips and Dalton’s Atomic Theory: Every element is made of atoms - piles of paper clips. All atoms of any element are the same - all the paper clips in the pile are the same size and color. Atoms of different elements are different (size, properties) - like different sizes and colors of paper clips. Atoms of different elements can combine to form compounds - you can link different sizes and colors of paper clips together to make new structures. In chemical reactions, atoms are not made, destroyed, or changed - no new paper clips appear, no paper clips get lost and no paper clips change from one size/color to another. In any compound, the numbers and kinds of atoms remain the same - the total number and types of paper clips that you start with are the same as when you finish. Each element is composed of extremely small particles called atoms All atoms of a given element are identical, but they differ from those of any other element. Atoms are neither created nor destroyed. A given compound always has the same relative numbers and kinds of atoms.
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4 Dalton's atomic theory rests on the following postulates.
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This note was uploaded on 01/26/2010 for the course CHEM 1311 taught by Professor Sussanthomas during the Spring '05 term at The University of Texas at San Antonio- San Antonio.

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lecture%207%20%28chapt5%29 - Chapter 5 Exam is not graded...

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