CHEM 177: CHAPTER 1
38 Cards in this Set
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Chemistry
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study of matter (materials) and its changes
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Everything in the Universe is either
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matter or Energy
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Matter
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occupies space â physical âmaterialâ of universe [has mass]
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Energy
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ability to do work or transfer heat
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Matter consists of
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Particles
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Atom
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âbuilding blocksâ of matter (the letters of a language)
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elements
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Materials of atoms of only one type make up
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Atoms of more than 1 element CAN make up
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molecules.
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Gas
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molecules or atoms very far apart, moving rapidly, the container entirely filled with the species (3-D)
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Liquid
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molecules or atoms in close proximity, moving, take on shape of vessel
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Solid
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fixed volume and shape. molecules/atoms â rigid.
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Law of constant composition or law of definite proportions
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for a given compound, the composition is always the same; the ratio of the constituent atoms is constant. For example: natural gas always has the composition: 4 hydrogen atoms for every 1 carbon atom.
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Law of multiple proportions
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different compounds may be formed from the same constituent elements in different, but fixed, compositions or ratios. For example: water and hydrogen peroxide consist of hydrogen and oxygen. In water the ratio of H atoms to O atoms is 2:1, for hydrogen peroxide, the ratio is 1:1. All wate…
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Same compound
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Same Properties
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Mixtures (Classifications of matter)
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mix of 2 or more pure substances (elements or compounds). Can have variable compositions
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Heterogeneous mixtures
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not uniform (concrete, cereal and milk)
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Homogeneous mixtures
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uniform throughout (metal alloys, air, solutions â salt water)
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Physical properties
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Physical properties â density, hardness, color, odor, melting point, boiling points. Measurable without changing composition.
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Physical changes
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change in state of matter or appearance without change in composition (evaporation, melting, condensation, freezing) may involve heat transfer.
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Chemical properties
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how substance reacts or changes to form other properties. Fe rusts â reacts with oxygen to form iron oxide.
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Chemical changes =
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reactions
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intensive properties
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independent of amount of material. density, color, temperature, reactivity, etc.
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extensive properties
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dependent upon amount of material. mass, volume.
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mixtures (Properties of Matter)
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can be separated into components by physical means distillation, filtering, evaporation, chromatography
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mass (measurement)
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kilogram kg
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length
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â meter m
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temperature
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Kelvin K
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Amount of substance â mole mol
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â mole mol
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electric current
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â Amp A
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micro
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10^-6 or 1/1,000,000 ï
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milli
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10^-3 or 1/1000 m
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centi
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10^-2 or 1/100 c
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kilo 103 or 1000 k
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10^3 or 1000 k
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Poem about Celsius:
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Zero is cold, 10 is not, 20 is warm, and 30 is hotâ¦
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V = (calculations)
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length3
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Density = (calculations)
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mass/volume
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Precision
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â measure of reproducibility
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Accuracy
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â how close to true result
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CHEM 177: CHAPTER 1