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Difference between natural and synthetic chemicals

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Unformatted text preview: omas Edison Section Test Questions 1. What is the difference between natural and synthetic chemicals? Which are toxic? 2. Which of the following describe a scientific theory: (a) tested, (b) explains observations, (c) known to be true, (d) repeatable? Answers 1. Natural chemicals occur in nature, whereas as synthetic chemicals are man-made. Toxicity is a property specific to a chemical, regardless of its origin. For example, alcohol (i.e., ethanol) is the same chemical (i.e., CH3CH2OH) regardless of whether it was made in nature by fermentation or synthesized in lab by a chemist. 2. A, b & d. Scientific theory is always vulnerable to change. 1.3 Matter Matter is anything that has mass and occupies space. It is the physical material of the universe. Chemistry helps us understand how matter is put together and helps us understand their properties. 1.3.1 States of Matter There are three states of matter (Figure 1.4): gas, liquid and solid. 10 Copyright © 2007 by Concise Books Publishing LLC. Visit us at www.concisechem.com to download other free chapters from "The Concise Guide to Chemistry." CHAPTER 1: INTRODUCTION TO CHEMISTRY Figure 1.2: The Three States of Matter They can be described on macroscopic and molecular levels (Table 1.1). For the sake of our descriptions below, definite means shape/volume is not defined by a container, whereas as indefinite means that shape/volume is defined by a container. A particle refers to atoms and/or molecules. Table 1.2: Macroscopic & Molecular Descriptions of States of Matter Description Macroscopic Molecular Gas • • • Indefinite volume Indefinite shape Particles are far apart with mostly empty space Liquid • • • Definite volume Indefinite shape Particles are tightly packed but can move past each other Solid • • • Definite volume Definite shape Particles are tightly packed Macroscopic View • Gas will take the size and shape of any container. For example, when you light a match, the smoke expands throughout the room. • Liquid will take the shape of the container but will not expand in volume. For example, when pouring a beer into a mug, it will take the shape of the beer mug but will not increase in volume (wouldn’t that be nice). • Solid has a definite volume and a definite shape. For example, a metal block will not change its shape nor volume regardless of the container it’s in. Molecular View • Gases have indefinite volume and shape because the gas molecules are far apart with mostly empty space. • Liquids can change their shape because particles can move past each other. • Solids have definite volume and shape because their particles are tightly packed. Inquisitive Chemist 1.6: “Fourth” and “fifth” states of matter. You usually learn of only three states of matter because those are the only states of matter that are prevalent on our planet. However, two additional states of matter do exist under different conditions. 11 Copyright © 2007 by Concise Books Publi...
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