Chapter 1 Notes

Chapter 1 Notes - Chapter 1 Notes 20 January 2008 Chemistry...

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Chapter 1 Notes 20 January 2008 Chemistry and Matter -Chemistry is the study of matter, also considered the central science. -Matter is anything that has mass and occupies space. -Mass is the amount of a certain substance; an object’s mass never changes. -Weight, on the other hand, measures the gravitational force between two objects; an object’s weight changes with altitude. States of Matter -In a solid, the particles are close together, thus having a definite shape and volume; it’s a highly compressed state of matter. -In a liquid, the particles are not as close together—they’re free to move around. Liquids have a definite volume, but do not have a definite shape. -In a gas, the particles are scattered and move freely and does not have a definite shape or volume. -Physical/Chemical Changes -A physical change is where the chemical make up of a substance does not change, only the physical appearance; the substance can be put back into its original form. -A chemical change is where the chemical make up of a substance changes and the process is not reversible. -A combustion is the rapid combination of oxygen with a substance. CH 4 + 2O 2 CO 2 + 2H 2 O + heat -A complete combustion is when reactants break down into carbon dioxide and water (good). C x H y + O 2 xCO 2 + yH 2 O + heat -An incomplete combustion is when reactants break down into carbon monoxide and water (bad). C x H y + O 2 xCO + yH 2 O + heat Classification of Matter -Elements -An element is a pure substance—that is, they have a definite composition. -Elements are substances that cannot be broken down into simpler ones by any chemical means. -There are over 100 elements, and all common forms of matter are composed of them. -About 90 elements occur naturally on planet Earth and, as far as we know, in the universe. The other 10 or so elements have been created from existing elements through artificially induces nuclear reactions. -Compounds -Compounds are also pure substances that consist of two or more elements (fixed composition) that can be broken down. -Mixtures -The air we breathe is a mixture—a physical combination of two or more substances with variable amounts. -Heterogeneous mixture—a nonuniform mixture (mixing salt and pepper)
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Chapter 1 Notes - Chapter 1 Notes 20 January 2008 Chemistry...

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