Biology-Chapter 2 section 2 (properties of water)

What properties of water make it important to living things?

1. good solvent 2. less dense as a solid 3. high specific heat 4. cohesion/adhesion

mixture

a material composed of two or more elements or compounds that are physcially mixed together but NOT chemically combined

solution

a type of mixture in which all of the components are evenly distributed

Why is ice less dense than water?

as water cools, molecules slow down and get closer and closer together, until at 4 degrees, molecules are so close to each other that like charges repel, causing it to expand into a crystalline structure (which is a regular repeating pattern of hydrogen bonded water molecules)

Why does water have a high specific heat (absorbs heat without changing temperature very much)?

because it requires a lot of heat to break up the hydrogen bonding, so it can absorb or release large amounts of heat with relatively little change in temperature

cohesion

is the attraction between water molecules (due to Hydrogen bonding); creates surface tension (the "film" on top of water)

adhesion

is the attraction of water molecules to other materials

polar molecule

molecule in which the charges are unevenly distributed

Hydrogen Bonding

the attractive force between the hydrogen on one molecule of water and the oxygen on another molecule

Why is water polar?

the oxygen in a water molecule has a stronger pull on the shared electrons, making one end slightly negative and the other (where the Hydrogen's are) slightly positive

solvent

the substance in which the solute is dissolved (the substance doing the dissolving)

solute

the substance that is dissolved

hydrophobic

water fearing --- does not like to mix with water

hydrophilic

water loving --- likes to mix with water