University:
Missouri State University
Course:
CHM 460 | Environmental Chemistry: Water and Land
Academic year:

2021
Views:

390

Pages:

2
Author:

coolcait7128jzy

honors Name: _____________________________________________ Period: ________ Date: ____________ Properties of Water What Makes Water So Special? Why? When you hear that NASA’s space probes are looking for “evidence of life” on other planets, do you know what that means? They are looking for evidence of liquid water. Water is fundamental for all life; without it every living thing would die. Water covers about 70% of Earth’s surface and it makes up 65– 75% of our bodies (82% of our blood is water). Even if water might seem boring to you—no color, taste, or smell—it has amazing properties that make it necessary for supporting life. Model 1 – The Molecular Structure of Water = electron presence Oxygen Covalent Bond Electron density model of H2O 1. How many hydrogen atoms are in a molecule of water? 2. How many oxygen atoms are in a molecule of water? Hydrogen Hydrogen 3. What holds the hydrogen atoms to the oxygen atom? 4. The shading around the molecule represents the relative density of electrons shared by the atoms. What does this indicate about the density of electrons around the oxygen atom as compared to the density of electrons around the hydrogen atoms? 5. Where is the majority of negative charge on the water molecule? Model 2 – Attraction of Water Molecules Looking at your answers to Questions 1 and 2 from Model 1, tell what atoms are represented by: a. b. c. d. The small, unshaded circles: ___________________ The larger gray shaded circles: __________________ The solid black lines: ___________________ The dotted lines: ___________________ Weak attraction 1. Remember that electrons in a water molecule are more dense around the oxygen atom and less dense around the hydrogen atoms. a. What kind of charge would the oxygen atom have compared to the hydrogen atoms? b. What kind of charge would the hydrogen atoms have compared to the oxygen? 2. Describe the arrangement of the water molecules in Model 2 with one another. 3. Describe the cause of the attractions between molecules of water. 4. If another water molecule was added to the group in Model 2 at the upper right side, which of its atoms would be connected to the existing molecule with a dotted line? Describe your group’s reasoning. Read This! The bonding electrons in some molecules are not equally shared between the atoms. These neutral molecules with a difference of charge across the molecule are called polar molecules. Because of the arrangement of the atoms and electrons in a water molecule, there are two differently charged areas of the molecule even though the molecule is neutral overall. The hydrogen molecules are slightly positive, while the oxygen is slightly negative. The positive area charge (hydrogen) of one water molecule is attracted to the negative area (oxygen) of a different water molecule. This weak attraction is often referred to as hydrogen bonding. 5. In the space below, draw 10 water molecules to create a cluster. Be sure to indicate the hydrogen bonds that link the water molecules.

What Makes Water So Special

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