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# Chem unit 1 (ch 1-5)

Question | Answer |
---|---|

What is chemistry? | The study of matter and the transformation it undergoes. |

Chemical | If it has matter and takes up space. |

What is diatomic molecules? | Always stuck together. (Ex- O2) |

Molecular level | The behavior of matter |

Example of a checmical formula | H2O |

Example of a structural formula | O / \ H H |

What’s the scientific method? | Method of learning that emphasizes observation and experimentation to understand the world. A continuous creative process by which people learn about the physical universe. |

What does scientific method provide? | Fundamental foundation for the methods of science. |

Steps of the scientific method. | 1) observations 2) hypothesis- an educated guess that can be tested 3) experiment 4) model (theory) 5) further experiment |

What is a scientific law? | A brief statement that synthesizes past observations and predicts future ones. |

What is a theory ? | A unifying principal that explains what we observe in terms of underlying causes. |

Natural law | Tells you what |

Theory | Tells you why |

What is 200 years old with experimental evidence to support it including images of atoms? | Atomic theory |

What are the 2 main types of mathematical problems? | 1) unit conversion 2) word problems |

Common language | The order to communicate across out world we use this for units and equations. |

Scientific notation | Way of writing large and small numbers. |

Large #s | Whenever you move your decimal left you multiple by 10 |

Small #s | Whenever you move your decimal over to the right you divide by 10 |

Measured values | Have an uncertainty. For scientific numbers that are measured every digit is certain except the last, which is estimated. |

Precision | How closed are the dada points to one another |

Accuracy | How close the measurements to the true value |

Exact numbers | Do not have any uncertainty with them |

Measurements | Length (meter in metric) Mass (grams in metric) Volume (liters in metric) |

Values that are measured (uncertain at end) 1) all non-zero digits are significant 2) leading zeros aren’t significant 3) if zero is sandwiched between numbers it’s significant 4) end zeros with no decimals are not significant. | Significant figures |

Multiplication or division | Answer will have the same as the fewest of significant figures in calculation. |

Addition or subtraction | Same number of decimal places as the FEWEST of decimal places. Round down if 4 or less. Round up if 5 or more. (Last digit) |

Negative exponent | Same as writing unit in denominator. |