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27 Cards in this Set
- Front
- Back
Matter
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anything that takes up space and has mass
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Chemistry
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a science that studies the composition and properties of matter, and the changes that matter undergoes.
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Atoms
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the smallest distinctive units in a sample of matter
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Molecules
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larger units in which two or more atoms are joined together
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Gas (Vapor)
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matter that has no fixed volume or shape (conforms to the container)- can be compressed to fit a much smaller volume- can expand to fill larger volume. The particles of a gas are FAR apart and moving at high speeds- colliding with each other- and walls of container
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Liquid
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matter that has a distinct volume independent of its container but has NO specific shape- will assume the shape of the container and cannot be compressed appreciably. particles are not as far apart as in gas phase- still move rapidly- allowing them to slide, glide, and rotate past and over each other- will "pour"
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Solid
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matter that is rigid and cannot be compressed to an appreciable extent- the atoms and molecules are held tightly together, usually in definite arrangements- in which the molecules can wiggle and vibrate only slightly in otherwise fixed positions.
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Kinetic Energy
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the energy associated with an object by virtue of its motion. An object of mass m and speed or velocity v has a kinetic energy Ek equal to: Ek= (1/2) mv^2
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Intramolecular Forces
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forces within a molecule- electrostatic attractions that produce chemical bonds between atoms (ionic and covalent)
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Intermolecular Forces
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electrostatic attractions between molecules
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Kinetic Molecular Theory
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all matter is in constant motion and as it is heated, the particles move faster, and as the particles are cooled, they move slower
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Matter can be classified into two main categories of 1)_________ ________ and 2)_________
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1) Pure Substances
2) Mixtures |
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Pure Substances
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matter that has a fixed composition and distinct properties (either elements or compounds) (have constant boiling points-- mixtures do not!)
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Elements
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matter that cannot be broken down into other simple substances by chemical reaction or decomposition. Each element is composed of its own kind of atom identified by their symbols
ex. Carbon- C, Mercury- Hg |
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Compounds
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a substance made up of atoms of two or more elements, with the different kinds of atoms combined in fixed proportions by mass. Compounds CAN be broken down into elements by chemical reactions. (properties of compounds are different from those of the elements they contain)
ex. NaCl, H20 |
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Mixtures
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(comprise most of the matter we encounter!) Matter that has no fixed composition and are combinations of two or more pure substances in which each pure substance maintains its own chemical identity and therefore, properties
(the substances making up a mixture are called components of the mixture- these can be separated) |
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Homogeneous Mixture
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a mixture that has the same composition and properties throughout-- also known as a SOLUTION
ex. air, thoroughly dissolved salt in a glass of water |
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Heterogeneous Mixture
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a mixture that varies in composition and/or properties from one part of the mixture to another
ex. sand in a bucket, cement |
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Law of Definite Proportions (or Law of Definite Composition)
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states that the elemental composition (or ratio by atomic mass) of a pure compound is always the same.
ex. H202= 2(1): 2(8) = 2:16 = 1:8 |
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Law of Multiple Proportions
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states the fact that it IS possible for two or more compounds, with different ratios by mass of the same elements, to be made
ex. CuO and Cu2O |
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Separation of Mixtures
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since each component of a mixture retains its own properties, we can separate a mixture by taking advantage of their different properties
ex. filtration, by color, reactivity, boiling points, etc. |
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Physical Properties
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characteristics displayed by a sample of matter without undergoing any change in its composition
ex. odor, color, density, boiling point, etc. |
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Chemical Properties
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characteristics displayed by a sample of matter as it undergoes a change in its chemical composition- they describe the way a substance may change or react to form other substances
ex. combustibility, reactability with acids |
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Intensive Properties
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do NOT depend on the amount of the sample
ex. temperature, density, melting point |
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Extensive Properties
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DO depend on the quantity/amount of the sample
ex. measurements of volume and mass |
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Physical Changes
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when a sample of matter undergoes a noticeable change at the macroscopic level, but has NO change in composition.
~ALL PHASE CHANGES |
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Chemical Changes
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(also chemical reaction) a sample of matter undergoes a change in composition and/or the structure of its molecules
ex. cooking foods, combustion of ethyl alcohol |