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Matter: Properties & Changes. Chapter 2 notes. can be observed or measured without changing the composition of the sample Examples: color, phase, melting or boiling point, density, hardness, odor, taste. (2.1) Physical Properties of Matter. States of Matter.
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Matter: Properties & Changes Chapter 2 notes
can be observed or measured without changing the composition of the sample Examples: color, phase, melting or boiling point, density, hardness, odor, taste (2.1) Physical Properties of Matter
States of Matter • Solid (s) - definite volume and shape • Liquid (l) - definite volume, but not shape • Gas (g) - no definite volume or shape • Plasma - highly ionized gas (g) (s) (l)
sToP & tHinK • Which state or states of matter take(s) the shape of its container? • Which state or states of matter can change in volume (without adding or subtracting from the sample)?
Physical Changes • Physical changes alter a substance without changing its composition
sToP & tHinK • Which of the following are physical properties? • liquid at room temperature • reacts with metals to form H2 gas • acids and bases combine to form water and a ‘salt’ • boils at 145 degrees Celsius
(2.2) Mixtures… • Mixture - a combination of two or more pure substances, in which each substance retains its individual chemical properties • Heterogeneous mixture - does not blend smoothly, individual substances are distinct • Homogeneous mixture - solution; has a constant composition throughout
sToP & tHinK • Heterogenous or Homogeneous? (1) (2)
Separating Mixtures • Filtration - porous barrier separates solid from liquid • Distillation - liquids separated by differences in boiling point • Crystallization - forms pure solids from dissolved substances • Chromatography - separation based on ability to travel or be drawn across a material
sToP & tHinK What separation technique is shown in the following pictures? B A
(2.3) Elements & Compounds • Elements - pure substances that cannot be broken down into simpler substances • on the Periodic Table! • Compounds - two or more elements bonded together that can be broken down
sToP & tHinK • In your own words, what is the difference between an element and a compound? • Classify the following as being elements or compounds • Sodium • Sodium chloride • Oxygen • Carbon dioxide • Copper
the ability of a substance to undergo chemical change Examples: “reacts with oxygen to form rust”, “forms a deep blue solution when in contact with ammonia” (2.4) Chemical Properties
Chemical Changes • Chemical changes alter the composition so that a new substance forms • Evidence of chemical change: formation of a gas or solid (precipitate), smoke, fire, an odor, temperature change, color change • Law of Conservation of Mass: composition changes, but mass doesn’t
sToP & tHinK • Substance A is a yellow liquid and substance B is a blue liquid. The two are mixed and form a green liquid and a white solid. • What evidence suggests a chemical change occurred? • What other things could you look for to determine if there was a chemical change?
sToP & tHinK - which shows physical change and which shows chemical change? • link to change animation #1 • link to change animation #2