Lesson 3: Properties Of Water Flashcards
(26 cards)
Why is water considered inorganic?
It does not contain carbon.
What type of bond holds the atoms in a water molecule together?
Covalent bond (specifically, a polar covalent bond).
Why is water a polar molecule?
The shared electrons spend more time around the larger oxygen atom, giving oxygen a partial negative charge and hydrogen a partial positive charge.
What is a hydrogen bond?
A weak attraction between a partially positive hydrogen and a partially negative atom (like oxygen or nitrogen).
How strong are hydrogen bonds compared to covalent and ionic bonds?
Hydrogen bonds are weak and easily broken, but when numerous, they have a large effect.
What do hydrogen bonds explain about water?
They explain many of water’s unique properties, like cohesion and high heat capacity.
What percentage of the human body is water?
70%
Why is water essential for cell function?
Only substances dissolved in water can cross the cell membrane (e.g., glucose, amino acids).
How does water help remove waste from the body?
It carries away dissolved wastes through sweat and urine.
Name one way ions in solution are important for the body.
Calcium (Ca²⁺) is needed for movement; sodium (Na⁺) and potassium (K⁺) are necessary for nerve impulses.
How does water protect joints?
Joints are lubricated by a watery fluid.
How does water protect the brain?
A watery layer helps cushion the brain against shock.
How does water help maintain body temperature?
It absorbs and retains heat, preventing rapid temperature changes.
Where is water abundant?
Throughout the biosphere.
Where did life begin?
Water
How does hydrogen bonding affect water’s freezing and boiling points?
It lowers the freezing point and raises the boiling point, keeping water liquid at body temperature.
Why does water absorb and release heat slowly?
Due to hydrogen bonding, water resists temperature changes, helping maintain stable environments (e.g., ocean temperatures and cooling through sweating).
What is cohesion?
The ability of water molecules to stick to each other due to hydrogen bonding.
How does cohesion help transport substances?
It allows water to move through tubes (like blood vessels and plant stems) by pulling along dissolved substances.
What is surface tension?
The cohesive force at the surface of water that forms a “skin,” allowing small objects or insects to stay on the surface.
How can surface tension be reduced?
Some substances (like soap) weaken the cohesive forces of water, breaking the surface “skin.”
How does water’s density change when it freezes?
Unlike most substances, water expands when it freezes, making solid ice less dense than liquid water.
Why does ice float on water?
It insulates water below, protecting aquatic life in cold environments.
Why is water called the “universal solvent”?
It dissolves many substances, especially polar molecules, due to its polarity and hydrogen bonding.
