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Chapter 3 - Water and Life
Terms in this set (12)
Why is water so unique?
Water is the only common substance to exist in the natural environment in all three physical states of matter.
What is the shape of water molecules?
A water molecule is in a shape of a wide "V" with two hydrogen atoms (small) on the top ends of the "V", while the oxygen atom is on the bottom end of the "V"
What bonds are present within a water molecule?
Each hydrogen atom is bonded to the oxygen in a wide "V" shape via single polar covalent bond. Since the oxygen is more electronegative than the hydrogen, the shared valence electrons spend more time near the oxygen -- ultimately, making the oxygen negatively charged and the hydrogen positively charged.
What determines the overall charge of a molecule?
The shape of the molecule and the unequal/equal share of electrons determines the overall charge of a molecule
When is a molecule considered a polar molecule? Use water as an example.
a molecule is considered a polar molecule when there is an uneven distribution of charges in different regions of the molecule.
For example, water is in the shape of a V and has a polar covalent bond in which the shared valence electrons spend more time closer to the oxygen, making the whole water molecule having unevenly distributed charges.
How strong is the hydrogen bond in water's liquid form?
Hydrogen bond in water's liquid form is weak, each only about 1/20 as a covalent bond, leading them to form, break, and reform in great frequency and ultimately having such extraordinary properties
What four emergent properties of water contribute to Earth's sustainability as an environment for life?
cohesive (adhesive) behavior, ability to moderate temperature, expansion upon freezing, and versatility as a solvent.
What is cohesion? Use water to explain.
Cohesion is the linking of like molecules, often by hydrogen bonds.
Even though the arrangement of molecules in liquid water is constantly changing, the water molecules are linked by multiple hydrogen bonds at a time. Due to this, water is more structured than other liquids and the substance is held together.
What is adhesion?
Adhesion is the clinging of one substance to another, such as a water to plant cells by means of hydrogen bonds.
How is this cohesive behavior of water important for transportation of water and dissolved nutrients in plants? Also, does adhesion play a role in this at all?
As water evaporates from a leaf, the hydrogen bond (cohesive behavior) causes the water molecules traveling up the vein to pull on water molecules further down.
Yes, adhesion does help with the transportation of water and dissolved nutrients in plants, as the adhesion of water by hydrogen bond to molecules of plant walls helps counter the downward pull of gravity.
What is surface tension? Is water's surface tension weak or strong? Why?
Surface tension is how difficult it is to stretch or break the surface of a liquid. Water has high surface tension because of the hydrogen bonding of surface molecules.
How does water
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