It’s weird!! And that’s good!

Water and Living Things Agriculture Industry Transportation Recreation Growth, Reproduction & other important processes.

Picture of Earth showing if all Earth's water (liquid, ice, freshwater, saline) was put into a sphere it would be about 860 miles (about 1,385 kilometers) in diameter. Diameter would be about the distance from Salt Lake City, Utah to Topeka, Kansas, USA.

Water’s Unique Structure three A water molecule (H 2 O), is made up of three atoms --- one oxygen and two hydrogen. H H O

slightly positive charge slightly negative charge hydrogen bond between (+) and (-) areas of different water molecules Water molecules form Hydrogen bonds

Formed between a highly Electronegative atom of a polar molecule and a Hydrogen Formed between a highly Electronegative atom of a polar molecule and a Hydrogen One hydrogen bond is weak, but many hydrogen bonds are strong One hydrogen bond is weak, but many hydrogen bonds are strong

BrainPop time!

Section 1 Review What percent of Earth’s water is salt water? What percent is fresh water? Where is most of the fresh water on Earth found?

Unique Properties of Water (it’s weird!) Cohesion Surface tension Adhesion Capillary Action The Universal Solvent Specific Heat Boiling/Freezing

Cohesion Water clings to polar molecules through hydrogen bonding – Cohesion refers to attraction to other water molecules. responsible for surface tension – a measure of the force necessary to stretch or break the surface of a liquid

Surface Tension the tightness across the surface of water that is caused by the polar molecules pulling on each other the molecules at the surface are being pulled by the molecules next to them and below them the pulling forces the surface of the water into a curved shape

– Adhesion refers to attraction to other substances. Water is adhesive to any substance with which it can form hydrogen bonds. Adhesion

Adhesion Also Causes Water to … Form spheres & hold onto plant leaves Attach to a silken spider web

Are you wondering what the difference is between cohesion and adhesion?....

Capillary Action Because water has both adhesive and cohesive properties, capillary action is present. Capillary Action = water ’ s adhesive property is the cause of capillary action. Water is attracted to some other material and then through cohesion, other water molecules move too as a result of the original adhesion. Ex: Think water in a straw Ex: Water moves through trees this way

Capillary Action

Water, the Universal Solvent Water is “polar” The charged ends of the water molecule attract the molecules of other polar substances Solvent vs. Solute It dissolves more substances than any other liquid wherever water goes, it takes along valuable chemicals, minerals, and nutrients.

Specific Heat Amount of heat needed to raise or lower 1g of a substance 1° C. Amount of heat needed to raise or lower 1g of a substance 1° C. Water resists temperature change, both for heating and cooling. Water resists temperature change, both for heating and cooling. Water can absorb or release large amounts of heat energy with little change in actual temperature. Water can absorb or release large amounts of heat energy with little change in actual temperature.

A large body of water can absorb a large amount of heat from the sun in daytime and during the summer, while warming only a few degrees. At night and during the winter, the warm water will warm cooler air. Therefore, ocean temperatures and coastal land areas have more stable temperatures than inland areas. The water that dominates the composition of biological organisms moderates changes in temperature better than if composed of a liquid with a lower specific heat. Impact of water’s high specific heat ranges from the level of the whole environment of Earth to that of individual organisms.

Changing States of Matter Melting Boiling & Evaporation Condensation Freezing

Why Ice Floats Ice is less dense Ice is less dense as a solid than as a liquid hydrogen bonds constantly being broken and reformed. Liquid water has hydrogen bonds that are constantly being broken and reformed. Frozen water crystal-like lattice Frozen water forms a crystal-like lattice whereby molecules are set at fixed distances.

Ice is less dense than water: the molecules are spread out to their maximum distance Density = mass/volume

Which is ice and which is water?

 water expands as it solidifies  water reaches maximum density at 4-degrees C  water freezes from the top down  organisms can still live in the water underneath the ice during winter Oceans and lakes don’t freeze solid because ice floats

High Heat of Vaporization Amount of energy to convert 1g or a substance from a liquid to a gas Amount of energy to convert 1g or a substance from a liquid to a gas In order for water to evaporate, hydrogen bonds must be broken. In order for water to evaporate, hydrogen bonds must be broken. As water evaporates, it removes a lot of heat with it. As water evaporates, it removes a lot of heat with it.

540 cal/g. Water's heat of vaporization is 540 cal/g. In order for water to evaporate, each gram must GAIN 540 calories (temperature doesn’t change o C). In order for water to evaporate, each gram must GAIN 540 calories (temperature doesn’t change o C). As water evaporates, it removes a lot of heat with it (cooling effect). As water evaporates, it removes a lot of heat with it (cooling effect).

Section 2 Review What causes water molecules to be attracted to each other? Why does sugar dissolve well in water? What unusual fact about ice causes it to float in liquid water? If you place a cup of sand and a cup of water in the sun, which one will het up faster? Explain your prediction in terms of a property of water.

The Water Cycle Section 3 Review What is the source of the energy that drives the water cycle? How might cutting down trees affect the amount of evaporation in an area?

BrainPop Time!