Module 02 — Life's Origins · quiz worth 22 pts · 2026-09-03
By the end you can
The vocabulary list looks long, but most of it grows from one cause: water has partially charged ends.
Build the chain once, then attach each property to it.
Oxygen pulls shared electrons closer than hydrogen does. Oxygen becomes partially negative; hydrogen becomes partially positive.
The molecule has two different partial-charge regions even though its overall charge is zero.
The positive end of one water molecule attracts the negative end of another.
Those attractions create cohesion, surface tension, high specific heat, high heat of vaporization, and the open structure of ice. Polarity also supports adhesion and dissolving charged materials.
What is the cause chain behind most properties of water?
Uneven electron sharing makes water polar; opposite partial charges form hydrogen bonds; those attractions create the properties.
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An element cannot be broken into other substances by chemical reactions. An atom has positive protons, neutral neutrons, and negative electrons. Atoms form compounds when they bond. H₂O tells you that one water molecule has two hydrogen atoms and one oxygen atom.
In ionic bonding, atoms gain or lose electrons to become ions; opposite ions attract, as in sodium chloride. In covalent bonding, atoms share electrons. Polar covalent bonding is a type of covalent bonding with unequal sharing. Hydrogen bonding is the weaker attraction between appropriate partially charged regions of molecules.
H₂O has two hydrogen atoms and one oxygen atom. Polar covalent bonds hold H and O together within one molecule because they share electrons unevenly. Oxygen pulls the shared electrons closer, making its end partially negative (δ−) and the hydrogen ends partially positive (δ+).
Opposite partial charges on neighboring water molecules attract. That weaker attraction between molecules is a hydrogen bond.
Cohesion is water attracting water. It makes droplets bead and strengthens the surface into surface tension. Adhesion is water attracting a different material, such as a plant vessel or paper towel. In a narrow space, adhesion pulls water along the surface while cohesion pulls more water behind it. Together they produce capillary action.
Sort the words by what is attracted.
Cohesion. At the surface, that produces surface tension.
Adhesion. Think glass, a leaf, or paper towel fibers.
Capillary action. Adhesion leads along the wall; cohesion brings the water column with it.
A paper towel pulls colored water upward. Name the two attractions.
Adhesion to the towel and cohesion between water molecules.
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Water dissolves more substances than any other liquid because its partially charged ends attract ions and other polar molecules. That lets water carry minerals, nutrients, and chemicals through soil and living things. Nonpolar substances such as lipids do not dissolve well in water because they do not have charged regions for water to attract.
Specific heat is the energy needed to change 1 gram of a substance by 1 °C. Water's high specific heat means it absorbs or releases a lot of energy with only a small temperature change. That steadies body temperature, ocean ecosystems, and coastal climates.
Heat of vaporization is the energy needed to turn 1 gram of liquid into gas. Water's hydrogen bonds take energy to overcome, giving water a high boiling point and making evaporation an effective way to carry heat away.
When water freezes, hydrogen bonds lock the molecules into an open, six-sided arrangement. The molecules spread farther apart than in liquid water, so the same mass takes more volume. Ice is therefore less dense and floats.
Floating ice forms an insulating layer. If ice sank, lakes and ponds could freeze from the bottom up and destroy the habitat below.
The frozen arrangement is the weird part.
Hydrogen bonds hold molecules in an open six-sided structure.
The molecules sit farther apart, so the same mass takes more volume.
More volume for the same mass means lower density. The floating layer insulates liquid water below.
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pH measures hydrogen-ion (H⁺) concentration on a 0–14 scale. Pure water is neutral at 7. Values below 7 are acids; lower pH means more H⁺. Values above 7 are bases; higher pH means less H⁺.
Course examples: battery acid and gastric fluid are strongly acidic; vinegar and lemon juice are acidic; pure water is neutral; seawater and baking soda solution are basic; household ammonia is more strongly basic.
The course review is a vocabulary match. These questions use those same definitions, plus the Biology Notebook's application questions. Explain the property before reading the feedback.
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