Presentation on theme: "Chapter 2: Matter & Change Matter- anything that has mass and takes up space Mass- amount of matter in an object Substance-matter that has a uniform and."— Presentation transcript:
Chapter 2: Matter & Change Matter- anything that has mass and takes up space Mass- amount of matter in an object Substance-matter that has a uniform and definite composition. Contains only one kind of matter. Ex: table sugar- always 100% sucrose. Has the same makeup or chemical composition All samples of a substance have identical physical properties. Ex: all sucrose tastes sweet and dissolves completely in water
Physical property- quality or condition of a substance that can be observed or measured without changing the substance’s composition. Ex: color, solubility, odor, hardness, density, melting point, boiling point, size, shape (table of physical properties of common substances pg. 29)
States of Matter State of Matter Particle arrange ment shapevolumeCompres sibility SolidsTightly compact definite Almost incompre ssible Liquids (can flow) Further apart indefinitedefiniteAlmost incompre ssible Gas or vapor Spread out far apart indefinite Readily compres sible
When heated, solids have a slight expansion, liquids a moderate expansion, and gas or vapor a great expansion. Gas- those substances that exist in the gaseous state at ordinary room temperature Ex: air- mixture of gases including nitrogen and oxygen Vapor- describes the gaseous state of a substance that is generally a liquid or solid at room temperature Ex: steam- gaseous form of water- liquid at room temperature
Physical change- alters a material without changing the composition Ex: cutting, grinding, bending, boil, freeze, dissolve, melt, condense, break, split, crack, crush Mixture-a physical blend of two or more substances. Composition may vary. Ex: blood, salad, iced tea, glass Two kinds of Mixtures: heterogeneous and homogeneous Heterogeneous mixture- not uniform in composition, not the same throughout, one portion differs from the other. Ex: salad, veggie soup, river water (consisting of two or more phases)
Homogeneous mixture- completely uniform throughout. Components are evenly distributed. Ex: salt water, cough syrup Solutions are homogeneous mixtures Phase- any part of a system with uniform composition and properties Homogeneous- 1 phase Heterogeneous- 2 or more phases Ex: oil & vinegar—2 phases, can see when left unshaken oil floats on the water.
Common Solutions Gas-Gas Ex: CO 2, O 2, N 2 (air) Liquid-Gas Ex: water vapor in air (fog, moist air) Gas-Liquid Ex: CO 2 in water (soda water) Liquid- Liquid Ex: acetic acid in water (vinegar) Solid-Liquid Ex: NaCl in water (brine) Solid-Solid Ex: copper in silver (sterling silver), brass (alloy)
Separating Mixtures Some mixtures can be separated into their components by simple physical methods Filtration-separate heterogeneous mixture. (separate solid from liquid) Evaporation- evaporate the liquid from the mixture Distillation- liquid is boiled to produce vapor that is then condensed again to a liquid. (pg. 34)
Elements- simplest forms of matter that exist under normal lab conditions, cannot be simplified by chemical means, building blocks of substances (Periodic Table of Elements) Compounds- two or more elements chemically combined, can be separated by chemical means Any sample of matter can be classified as an element, compound, or mixture (diagram pg. 38)
Chemical symbol- 1 or 2 letters represent an element, first letter always capitalized, second letter lowercase (Latin or Greek names used) Shorthand way to write chemical formulas of compounds Ex: C 6 H 12 O 6 Chemical Rx: 1 or more substances change into new substances Fe + O 2 FeO 2 (iron oxide, rust) (reactants) (products) Means to change into or produce
In a chemical rx: Energy is always absorbed or given off Change in color or odor Production of a gas or a solid from liquid (can also be physical change) Most chemical changes are not easily reversed Physical changes are usually reversible (change of state)
Conservation of Mass Quantity of matter is unchanged Mass of products = mass of reactants In any physical or chemical change/rx., mass is neither created nor destroyed, it is conserved.