Per. 4 Water as a Polar Molecule

What kinds of substances does water like to dissolve?

• polar substances

• non-polar substances

• substances with the same density

• substances with a different density

What are the three states of water? (MARK ALL THAT APPLY.)

• solid

• liquid

• gas

• goo

What property of water allows it to be such a versatile solvent that it is often called the "universal solvent?"

• Purity
• Polarity and cohesion
• High heat capacity
• Expansion upon freezing

Water striders can walk across the surface of calm water. Their feet push the surface of the water down slightly, but they do not break the surface. Why?

• The insects are light enough so they do not break the hydrogen bonds holding the water molecules together
  
• The insects actually use their wings to hover slightly above the water’s surface and they only skim it with their feet.
• The insect’s feet are non-polar, so they are repelled by the polar water molecules and are pushed away from the water’s surface.
• The insects are small enough to see the individual water molecules, so they are able to step carefully from one molecule to the next
  

What two elements make up water?

• Helium and oxygen
• Hydrogen and oxygen
• helium and carbon
• oxygen and carbon

Why can water have no net charge but have slight charges in different parts of the molecule?

• The oxygen end is slightly negative and the hydrogen end is slightly positive
• The hydrogen end is slightly negative and the oxygen end is slightly positive
• The hydrogen and oxygen ends change in polarity
• Because it is hydrophobic

The attraction that causes water and other liquids to form drops on thin films is called ________________. This is also water’s ability to be attraction to other water molecules.

• adhesion
• capillary action
• cohesion
• surface tension

Water is polar because...

• The unequal sharing of electrons gives the water molecule a slight negative charge near its oxygen atom and a slight positive charge near its hydrogen atoms.
• The molecule has two poles, at which the it is colder than other regions of the molecule.
• The unequal sharing of electrons gives the water molecule a slight negative charge near its hydrogen atoms and a slight positive charge near its oxygen atom.
• The water molecule is neutral.

Water is a universal solvent because it...

• It can be found anywhere
• It freezes when it gets cold
• floats when frozen
• Dissolves most substances

The atoms in a water molecule are held together by covalent bonds. This means that the bonded atoms

• Lose protons

• Lose electrons

• Share electrons

• Switch neutrons