_281_29_Elements_and_Chemical_Compounds lab for bio

Page 1: Introduction to Elements and Compounds

• Definition of Elements and Compounds

  • Pure chemical substances found in nature with distinct physical and chemical properties.

  • Elements consist of a single type of atom and cannot be separated into simpler substances.

    • Example: Silver remains silver regardless of how much it is broken down.

• Chemical Symbols

  • Each element is represented by a chemical symbol, consisting of 1-3 letters.

  • The first letter is always capitalized; subsequent letters are lower case.

    • Example: Carbon (C), Calcium (Ca).

• Properties of Elements

  • Unique physical properties used for identification regardless of the quantity.

    • Characteristics include boiling point, melting point, density, and magnetic behavior.

• Classification of Elements

  • Elements are primarily categorized as metals or nonmetals:

    • Metals:

      • Usually solid, good conductors of heat/electricity, malleable, and ductile.

      • Majority of elements (approx. 75%) are metals, located on the left and center of the Periodic Table.

    • Nonmetals:

      • Typically do not possess metallic properties, located on the right side of the Periodic Table.

• Definition and Composition of Compounds

  • Compounds are pure substances formed from two or more elements that are chemically combined.

  • Represented by chemical formulas that indicate the quantity of atoms present.

    • Example: Water (H2O) = 2 Hydrogen + 1 Oxygen.

Page 2: Compounds and Their Properties

• Understanding Compounds

  • Properties of compounds differ significantly from their constituent elements.

  • Elements combine to form compounds in specific ratios, which remain constant.

    • Example: H2O (water) has exactly 2 hydrogen and 1 oxygen atom.

    • Altering the ratio (e.g., H2O2) leads to different compounds with distinct properties.

  • Water is colorless and neutral; Hydrogen peroxide is also colorless but has acidic properties.

• Separation of Compounds

  • Compounds can only be separated into elements through chemical reactions.

• Objective of the Experiment

  • To learn and understand the differences between elements and compounds.

• Experimental Procedure

  1. Examine the elements and compounds on display and record observations on a data sheet.

  2. Important Notes:

     • Do not open individual jars, especially not the sodium jar, which is highly reactive.

     • Test for magnetic attraction using a magnet on the outside of the jars.

Page 3: Experiment Data Sheet - Elements

• Section A: Elements Data Sheet

  • Table for Observations (to be completed during the experiment):

    • | Name of Element | Symbol | Color | Physical State | Attraction to Magnet | Metal or Nonmetal |

    • |-----------------|--------|-------|----------------|---------------------|------------------|

    • | Carbon | C | | | | |

    • | Sodium | Na | | | | |

    • | Zinc | Zn | | | | |

    • | Sulfur | S | | | | |

    • | Lead | Pb | | | | |

    • | Iodine | I | | | | |

    • | Nickel | Ni | | | | |

    • | Iron | Fe | | | | |

Page 4: Experiment Data Sheet - Compounds

• Section B: Compounds Data Sheet

  • Table for Observations (to be completed during the experiment):

    • | Name of Compound | Formula | Color | Physical State | Elements in the Compound | Number of Each Element |

    • |-------------------------|------------------|-------|----------------|--------------------------|------------------------|

    • | Sodium chloride | NaCl | | | (Na, Cl) | |

    • | Lead sulfide | PbS | | | (Pb, S) | |

    • | Nickel (II) chloride | NiCl2 | | | (Ni, Cl) | |

    • | Carbon tetrachloride | CCl4 | | | (C, Cl) | |

    • | Lead (II) iodide | PbI2 | | | (Pb, I) | |

    • | Iron (III) chloride | FeCl3 | | | (Fe, Cl) | |

    • | Zinc sulfide | ZnS | | | (Zn, S) | |