Mrs. MacWilliams Academic Biology

I. Properties of Water 1. Liquid at most of Earth’s temperatures 2. EXPANDS WHEN IT FREEZES! -unlike most things that expand when they get hot 3. WORLDS GREATEST SOLVENT 4. MOST ABUNDANT COMPOUND 5. only natural substance that is found in all three states -- liquid, solid (ice), and gas (steam) -- at the temperatures normally found on Earth. BIll Nye Solid Liquid Gas BIll Nye Solid Liquid Gas

Properties of water continued 6. Freezing point: 0 o C/32 o F 7. Boiling point: 100 o C/212 o F 8. Water has a high specific heat index. This means that water can absorb a lot of heat before it begins to get hot.

9. Due to the uneven distribution of electrons between oxygen and hydrogen atoms…. Water is POLAR. This polarity allows for cohesion (to itself) and adhesion (to other things) to occur. 9. Due to the uneven distribution of electrons between oxygen and hydrogen atoms…. Water is POLAR. This polarity allows for cohesion (to itself) and adhesion (to other things) to occur. **Water is neutral overall, however, the hydrogens have a slightly positive charge and oxygen has a slightly negative charge.

II. Bonding 1. Hydrogen bonding - type of bond between an electronegative atom and a hydrogen atom bonded to another electronegative atom. *Only Oxygen, Fluorine, and Nitrogen can form hydrogen bonds a. Adhesion - Attraction between molecules of different substances. Example: Water & glass Example: Water & glass b. Cohesion - Attraction between molecules of the SAME substance. Example: Water drops on penny Example: Water drops on penny Hydrogen bonding

c. Hydrophilic – Molecules that form hydrogen bonds with water example: vinegar and water (mix together and don’t separate) example: vinegar and water (mix together and don’t separate) d. Hydrophobic - Molecules that can't form hydrogen bonds example: oil and water (do not stay mixed together) example: oil and water (do not stay mixed together)

Water bonding cont. 2. Surface tension – measure of how difficult it is to break the surface of the water RAFT SPIDER RAFT SPIDER Cohesion is stronger at the surface of the water

Water bonding cont. 3. Capillarity – the ability of water to move up through narrow channels *Water has a very high surface tension. Surface tension is responsible for capillary action. capillary actioncapillary action

Water bonding cont. 4. Each water molecule can hydrogen bond to 4 other water molecules. *See next slide to learn how to draw this diagram

You will be asked to draw this diagram on a quiz or test. solid lines are covalent bonds dotted lines are hydrogen bonds

III. Mixtures and Solutions 1. Mixture -Two or more compounds mix together, but do NOT chemically combine. 2. Solution- one substance DISSOLVED in another Sol v ent- dissol v es a substance Solute- the substance 3. Suspension - A mixture where materials do not dissolve, but separate and settle out Example: Garlic, onions, and bell peppers in Italian dressing (vinegar and water layer) Example: Garlic, onions, and bell peppers in Italian dressing (vinegar and water layer)

VIDEOS Properties of Water Properties of Water Properties of Water Properties of Water PAINFUL example of water SURFACE TENSION PAINFUL example of water SURFACE TENSION PAINFUL example of water SURFACE TENSION PAINFUL example of water SURFACE TENSION