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# UNIT ONE chemistry

### chemistry Unit One

Term | Definition |
---|---|

accuracy | refers to how close a measured value is to an accepted value |

chemistry | the study of matter and the changes it undergoes |

conclusion | a judgement based on the information obtained |

control | in an experiment, the standard that is used for comparison |

experiment | a set of controlled observations that test a hypothesis |

hypothesis | a tentative, testable statement or prediction about what is being observed |

independent variable | in an experiment, the variable that the experimenter plans to change |

mass | measure that reflects the amount of matter |

model | visual, verbal, and/or mathematical explanation of data collected from many experiments |

base unit | defined unit in a system of measurement that is based on an object or event in the physical world and is independent of other units |

qualitative data | information describing color, odor, shape of some other physical characteristic |

quantitative data | numerical information describing how much, how little, how big, how tall or how fast |

scientific law | describing a relationship in nature that is supported by many experiemtns |

scientific method | a systematic approach used in scientific study; an organized process used by scientists to do research and to verify the works of others |

theory | explanation supported by many experiments; is still subject to new experimental data, can be modified, and is considered valid if it can be used to make predictions that are proven true. |

weight | measure of an amount of matter and also the effect of Earth's gravitational pull on that matter. |

dependent variable | in an experiment, the variable that depends on the independent variable |

conversion factor | ratio of equivalent values used to express the same quantity in different units. it is always equal to one and changes the unit without changing its value |

density | the amount of mass per unit of volume; a physical property |

derived unit | a unit defined by a combination of base units |

dimensional analysis | systematic approach to problem solving that uses conversion factors to move from one unit to another |

error | differences between an experimental value and an accepted value |

graph | visual display of data |

kelvin | SI unit of temperature |

kilogram | SI base unit of mass |

liter | metric unit for volume; is equal to 1 cubic decimeter |

meter | SI unit for length |

percent error | ratio of an error to an accepted value |

precision | refers to how close a series of measurements are to one another, show little variation over a series of trials, but might not be accurate |

scientific notation | express any number as a number between 1-10 (coefficient) multiplied by 10 raised to a power (exponent) |

second | SI base unit for time |

significant figure | number of all known digits represented in a measurement plus 1 estimated digit |