AP Biology: Water

What is the formula for water?

H2O (2 hydrogen, 1 oxygen)

Which bonds are created between the hydrogen and oxygen atoms of a water molecule?

Polar Covalent Bonds

Which atom in water is electronegative and greedy for more electrons?

Oxygen

What is the charge for Oxygen in a water molecule?

Partial Negative

What is the charge for Hydrogen in a water molecule?

Partial Positive

What causes attraction between water molecules?

Polarity of water

What bond is created between water molecules because of the polarity of the water?

Hydrogen bonds

What causes water's properties?

Hydrogen bonds and polarity of water

What is cohesion?

Attraction between two water molecules

What does cohesion cause?

High surface tension

What does surface tension allow some organisms to do?

Walk on water

What is adhesion?

Water molecules sticking to other molecules that are not water.

What is capillary action?

When a liquid rises in a thin tube because the adhesive forces between the tube and the liquid are stronger than the cohesive forces between liquid molecules.

What is the universal solvent?

Water

What causes water to be the universal solvent?

Polarity of water

Solvents that can dissolve in water are

Polar and hydrophyllic

What does hydrophilic mean?

Water loving

How does water dissolve polar substances?

The polar substances create adhesive forces in water stronger than water's cohesive properties. The solvent breaks the hydrogen bonds between water and the hydrogen bonds form between water molecules and the solvent.

What does hydrophobic mean?

Water hating

What are hydrophobic substances?

Substances that are nonpolar and not able to be dissolved in water. They are being pushed away by the cohesive properties of water.

What is the only substance that is less dense as a solid than a liquid?

Ice

Why is solid water less dense than liquid water?

When reaching freezing point of water, hydrogen bonds solidify to create a crystalline structure that spaces water molecules more evenly. This creates less dense solid than liquid.

What is a benefit of less dense ice?

Allows for aquatic life form to stay alive when water freezes over.

What is a High Specific Heat?

Water requires a large amount of heat to be absorbed to increase temperature. Heat absorbed breaks hydrogen bonds.

What is a benefit of Water's high specific heat capacity?

Oceans don't heat up or cool down easily, allowing for regulation of temperature and climate on Earth.

How does sweating work?

When body gets hot, hydrogen bonds are broken and are evaporated away. When they escape, they take heat away from the skin, leaving the body cooler.