The Properties of Water Who Knew Water Could Do So Much!?! 1

Time To Explore Water’s Properties 2 Which property of water explains this ring of water?

Let’s Talk About Water 3 What percent of your body is water?

Water: H 2 O 3 atoms: One oxygen Two hydrogen H H O 4 “Mickey Mouse” Bent “Mickey Mouse” Bent shape

Water Unequal sharing of negative electrons between the oxygen and hydrogen atoms. Means that oxygen HOGS the negative electrons! In each water molecule, O atoms (-) attract (+) H atoms. H atoms (+), attract (-) O atoms 5

Hydrogen Bonds hold water molecules together (Oxygen attracted to a Hydrogen) 6

Van der Waals Forces The sum of all hydrogen bonds formed between a molecule and surrounding molecules

1. Water is “Polar” Uneven distribution of electrons between the 1 Oxygen and 2 Hydrogen atoms. universal solvent. Water’s polarity allows it to dissolve many things = universal solvent O H H

Solutions 9 Solutions Solutions : even distribution of Solute = substance to be dissolved Solvent =substance that does the dissolving

Ice is less dense than liquid water Water is less dense Water is less dense as a solid than as a liquid (therefore, ice floats) hydrogen bonds constantly being broken and reformed. Liquid water has hydrogen bonds that are constantly being broken and reformed. Ice that floats allows lakes to keep from freezing solid during winter Ice that floats allows lakes to keep from freezing solid during winter 10 Image

Ice is less dense than liquid water 11

Cohesion 12 Attraction between particles of the same substance (why water is attracted to itself) Because of Hydrogen Bonding, water is extremely cohesive. Results in Surface tension – a measure of the strength of water’s surface (like a surface film for insects to walk on)

Cohesion E xample: Surface Tension Image 13 video

Adhesion Attraction between two different substances (ex. glass, soil, plant tissues, cotton) capillary action Example: capillary action– process in which plants and trees remove water from the soil; or how paper towels soak up water Image 14

Gives water the ability to “climb” structures 15 Adhesion Example: capillary action REMEMBER! “D” for different!

Form spheres & hold onto plant leaves Attach to a silken spider web 16 Adhesion also causes water to…

High Heat Capacity 17 Watercan absorb a lot of heat Water can absorb a lot of heat before it gets hot. (It can absorb or release large amounts of heat energy with little change in actual temperature) Helps regulate temperature changes in areas close to oceans.

evaporates As water evaporates, it removes a lot of heat with it (cooling effect). broken In order for water to evaporate, hydrogen bonds must be broken. An example is sweating. 18 High Heat of Vaporization

A quick word about Mixtures, Solutions and Suspensions 19 Water is not always pure –often found in a mixture physical combination of 2 + things mixture: physical combination of 2 + things Water can make 2 types of mixtures: Solutions Solutions : even distribution of Solute = substance to be dissolved Solvent =substance the solute dissolves in

Solutions 20 Image

A quick word about Mixtures, Solutions and Suspensions 21 Suspensions : Suspensions : H 2 0 and non-dissolved material

Checking Your Knowledge “What Property?” 1.________allows water to dissolve a large variety of different salts and nutrients. The polarity of water makes it a good solvent 22

“What Property?” 2. ________ allows water to easily travel up the stem of a plant or a tree trunk. Capillary action or the adhesion of water molecules to other materials enables it to travel up the stems of plants and trees. 23

“What Property?” 3. ________ is the reason why the changing of the seasons from winter to spring is gradual, and why water is used in cooling radiators and power plants. High heat capacity of water means it can absorb large amounts of heat before it changes temperature. 24

“What Property?” 4. ________ allows small insects to walk across water. The high surface tension or cohesion of water means that an invisible film is on the surface of water allowing these small insects (and little lizard) to walk on water. 25

“What Property?” 5. ________ allows many land- dwelling organisms to maintain body temperature by eliminating excess heat? The high heat of vaporization means that water absorbs heat from the skin as it evaporates, thus cooling off the organism. 26

“What Property?” 6. If lakes were to freeze solid during the winter, the organisms living in there would die. Which property helps water prevent permanent freezing of lakes? Water is less dense as a solid so it floats when it freezes, and therefore insulates the rest of the lake/pond, etc. from freezing. 27