Elements, Compounds & Mixtures Worksheet



Elements and Compounds

Elements:

• A pure substance containing only one kind of __atom____.

• An element is always uniform all the way through (homogeneous).

• An element __cannot____ be separated into simpler materials (except during nuclear reactions).

• Over 100 existing elements are listed and classified on the _Periodic Table_.

Compounds:

• A pure substance containing two or more kinds of __atoms__.

• The atoms are ___chemically___ combined in some way. They come together to form groups of atoms called molecules, or large structures with repeating units of atoms called formula units.

• A compound is always homogeneous (uniform).

• Compounds ___cannot___ be separated by physical means. Separating a compound requires a chemical reaction.

• The properties of a compound are usually different than the properties of the elements it contains.

Classify each of the following as elements (E), compounds (C)

|E Diamond (C) |C Alcohol (CH3OH) |

| | |

|C Sugar (C6H12O6) |E Chlorine gas (Cl2) |

| | |

|E Iron (Fe) |C Ammonia (NH3) |

| | |

|C Sulfuric Acid (H2SO4) |C Salt (NaCl) |

| | |

|E Oxygen gas (O2) |E Gold (Au) |

| | |

|E Uranium (U) |C Baking Soda (NaHCO3) |

| | |

|C Water (H2O) |E Sulfur (S8) |

Match each diagram with its correct description.

[pic]

_C_1. Pure Element – only one type of atom present.

_E_2. Mixture of two elements – two types of uncombined atoms present.

_B_3. Pure compound – only one type of compound present.

_A_4. Mixture of two compounds – two types of compounds present.

_D_5. Mixture of a compound and an element.

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