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23 Cards in this Set
- Front
- Back
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Pure Substance |
*Pure Substance - matter that always has exactly the same composition
*composition means combining parts into a whole (pure substances or mixtures)
*has a fixed, uniform composition |
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Element |
*Element - a substance that cannot be broken down into simpler substances
*only around 100 elements stated (but there are many more)
*contains only one type of atom
*the smallest, uncuttable piece of a material |
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Atom |
*Atom - the smallest particle of an element
*an element has a fixed composition because it contains only one type of atom
*no two elements contains the same type of atom(s) |
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Compound |
*Compound - a substance that is made of two or more simpler substances and can be broken down into those simpler substances
*always contains two or more elements joined in a fixed proportion
*properties change when elements join and form compounds |
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Heterogeneous Mixture |
*Heterogeneous Mixture - the parts of the mixture are noticeably different from one another
*ex: grains of sand vary in size and color
*properties of a mixture can vary because the composition of a mixture is not fixed |
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Homogeneous Mixture |
*Homogeneous Mixture - the substances are so evenly distributed that it is difficult to distinguish one substance in the mixture from another
*ex: the water in a pool is a mixture of water and substances that dissolve in water
*the properties of a mixture can vary because the composition of a mixture is not fixed |
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Solution |
*Solution - the mixture that forms when substances dissolve and form a homogeneous mixture
*based on the size of its smallest particles, a mixture can be classified as a solution, suspension, or colloid
*the particles are too small to settle out of the solution |
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Suspension |
*Suspension - a heterogeneous mixture that separates into layers over time
*based on the size of its largest particles, a mixture can be classified as a solution, a suspension, or a colloid
*filters can be used to separate solids from liquids |
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Colloid |
*Colloid - contain some particles that are intermediate in size between the small particles in the solution and the larger particles in a suspension
*cannot use a filter to separate the parts
*ex: milk and fog
*don't separate into layers |
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Physical Property |
*Physical Property - any characteristic of a material that can be observed or measured without changing the composition of the substances in the material
*viscosity, conductivity, malleability, hardness, melting/boiling point, and density are all examples of the substances in the material(s)
*are used to identify a material, to choose a material, to separate substances
*color, taste, texture, smell, buoyancy |
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Viscosity |
*Viscosity - the tendency of a liquid to keep from flowing; resistance to flowing
*the viscosity of a liquid normally decreases when it is heated |
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Conductivity |
*Conductivity - a material's ability to allow heat to flow
*if a conductor can pass heat easily, it can normally pass electricity easily
*materials that have high conductivity (such as metals) are called conductors |
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Malleability |
*Malleability - the ability of a solid to be hammered without shattering
*ex: gold formed into jewelry
*most metals are malleable
*solids that shatter when struck are called brittle |
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Melting Point |
*Melting Point - the temperature at which a substance changes from a solid to a liquid
*ex: ice will melt to water (normally) around 0 degrees celsius |
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Boiling Point |
*Boiling Point - the temperature at which a substance boils
*ex: water will typically start to boil at 100 degrees celsius |
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Hardness |
*Hardness - the state or quality of being hard; solid and firm
*ex: diamonds scratching an object
*the ability of a material to be scratched, cut, or carved by (or do the same to) another material
*Moh's Hardness Scale
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Density |
*Density - the ratio of a material's volume to its mass
*density = mass (grams) / volume (centimeters3)
*can be used to test the purity of a substance |
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Physical Change |
*Physical Change - occurs when some of the properties of a material change, but the substances in the material remain the same
*some physical changes can be reversed, others cannot |
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Chemical Property |
*Chemical Property - any property that produces a change in the composition of matter
*ex: burning candle + oxygen in the air = water and CO2 (carbon dioxide)
*can be observed only when the substances in a sample of matter are changing into different substances |
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Flammability |
*Flammability - a material's ability to burn in the presence of oxygen
*materials that burn can be used as fuel(s)
*children's pajamas must have a low flammability |
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Reactivity |
*Reactivity - the property that describes how readily a substance combines chemically with other substances
*iron is highly reactive with oxygen (iron + oxygen = rust)
*oxygen is highly reactive |
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Chemical Change |
*Chemical Change - change that occurs when a substance reacts and forms one or more new substances
*to determine, compare materials before and after
*ex: burning match, darkened copper
*evidence for chemical change: change in color, production of gas, causes heat and/or light, forms a precipitate |
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Precipitate |
*Precipitate - a solid that forms and separates from a liquid mixture
*ex: orange fruit pulp in orange juice, milk clumps/cheese in milk |
