chemistry - This item is copyrighted and was created by...

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This item is copyrighted, and was created by those from “theeseller555.” The only authorized seller of this item is theeseller555. For TONS of practice problems, please go to: http://science.widener.edu/svb/tutorial/index.html http://chem.neopages.com/practice/ I. Atoms and Molecules II. States of Matter III. Chemical Reactions IV. Periodic Table V. Atomic Structure and Bonding VI. Energy VII. Thermodynamics VIII. Equilibrium IX. Acids and Bases X. Electro-chemistry XI. Nuclear Chemistry Atoms and Molecules Atoms and molecules make every tangible material in the universe. They are what make matter possible. Atoms combine with each other in two broad general ways: Molecular Compounds - sharing of electrons between atoms. Ionic Compounds - transfer of electrons from one atom to another Matter: Substances to refer to any particular variety of matter that always has the same properties an composition, regardless of how and where a specimen is obtained. For example, water is a substance. Under given conditions, any sample of water has the same properties and composition. The properties and composition can be used to identify water. On the other, hand wood is not a substance, it properties and composition can vary widely. Wood is actually a mixture of many substances.
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A sample of any substance is homogenous; that is the properties and composition are the same through out the sample. There are two major kinds of substances: 1. Elements - A substance that cannot be decomposed into two or more other substances by means of a chemical change is called an element. An element consists entirely of atoms with the same atomic number. Over one hundred and tentative different elements are known to exist. Most are metals such as mercury, iron, lead, copper, silver and gold. Others are nonmetals such as oxygen, sulfur, iodine and neon. Still others are semi-metals (metalloids) such as silicon beryllium and boron. 2. Compounds - A substance that can be decomposed into other substances by a chemical reaction is a compound. Every compound consists of two or more elements chemically combined in definite atomic proportions. For example, carbon dioxide is always two parts oxygen and one part carbon -- a ratio of 1:2 of carbon to oxygen. Please note that the properties of compounds are usually VERY different then those of the elements they come from. For example when hydrogen and oxygen, two gaseous elements, are combined in a 2:1 ratio, they form water. Mixtures - Like compounds, the components of a mixture are always composed of two or more elements, but mixtures differ from compounds in that: 1. The components of a mixture can either be elements or compounds. 2. The atomic ratio of compounds in a mixture is not fixed. 3. The properties of a mixture are always intermediate between those of its components.
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