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Classification of Matter. Chapter 1 Chemistry 2A. Chemistry : the field of study concerned with the characteristics, composition, and transformations of matter Matter : anything that has mass and occupies space Living and non-living Macroscopic and microscopic. States of Matter. Solids.
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Classification of Matter Chapter 1 Chemistry 2A
Chemistry: the field of study concerned with the characteristics, composition, and transformations of matter • Matter: anything that has mass and occupies space • Living and non-living • Macroscopic and microscopic
Solids • Definite shape • Definite volume • Atoms packed tightly together • May be crystalline or amorphous • Very low compressibility
Liquids • No definite shape • Definite volume • Atoms close together, but not locked into place • Low compressibility
Gases • No definite shape • No definite volume • Atoms/Molecules far apart • Compressible
Pure Substances • Element: a substance that cannot be decomposed or transformed into other chemical substances by ordinary chemical processes • Atom: smallest particle of an element that can exist and still have the properties of that element • Aluminum (Al), Carbon (C), Neon (Ne), Potassium (K)
Compound: A substance consisting of two or more different atoms chemically bonded in a fixed ratio • NaCl, CO2 • Ionic compounds and molecules
Mixtures • Mixtures: combinations of two or more pure substances in which each substance retains its own identity • Heterogeneous Mixture: a substance in which elements and/or compounds are blended together in such a way that there is no uniform composition or fixed ratio of the components of the mixture • Examples: Oil and water, mixed nuts
Homogeneous Mixture: A substance in which the different elements/compounds being mixed exist in definite ratios, but are not chemically bonded • Consists of two or more substances in the same phase • No amount of magnification will reveal an interface • Called a “solution” • Examples: Salt water, sugar water, O2 dissolved in water
Problems • Decide whether the following mixtures are heterogeneous or homogenous • Chocolate chip cookie dough • Wine • Milk • O2 in water • Chicken noodle soup • Kool-Aid
Physical Properties • Properties of an object or substance that can be measured or perceived without changing the identity of the substance
Extensive Properties: properties that depend on the amount of substance present Mass Volume Intensive Properties: properties that do not depend on the amount of substance present M.P. B.P. Classification of Physical Properties
Physical Change • A change in a physical property of a substance • Same substance before and after the change
Chemical Property • Any property of a material that becomes evident during a chemical reaction • Qualities that become evident by changing a substance’s identity • Capability to undergo chemical reactions • Flammability • Acidity • Corrosiveness • Toxicity
Chemical Change • A process in which reactants are changed into one or more different products • Have breaking and making of chemical bonds • chemical reaction
Problems • Decide whether the following are chemical or physical changes • Sawing a log in half • Melting chocolate in a pot on your stove • Burning your chocolate • Dissolving a nickel in acid • Cutting your hair