End Show Slide 1 of 44 Copyright Pearson Prentice Hall 2-2 Properties of Water

End Show 2-2 Properties of Water Slide 2 of 44 Copyright Pearson Prentice Hall The Water Molecule Water is the single most abundant compound on earth – 75% of the earth is covered in water. Water is the most abundant compound in living things – about 70% by mass in living things. Like all molecules, a water molecule is neutral.

End Show 2-2 Properties of Water Slide 3 of 44 Copyright Pearson Prentice Hall The Water Molecule Water is a polar molecule A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms.

End Show 2-2 Properties of Water Slide 4 of 44 Copyright Pearson Prentice Hall The Water Molecule Hydrogen Bonds Because of their partial positive and negative charges, polar molecules can attract each other. This is a type of Van der Waals force.

End Show 2-2 Properties of Water Slide 5 of 44 Copyright Pearson Prentice Hall The Water Molecule Hydrogen bonds are not as strong as covalent or ionic bonds Water’s ability to form multiple hydrogen bonds is responsible for many of its special properties.

End Show 2-2 Properties of Water Slide 6 of 44 Copyright Pearson Prentice Hall The Water Molecule Hydrogen bonds form between water molecules.

End Show 2-2 Properties of Water Slide 7 of 44 Copyright Pearson Prentice Hall The Water Molecule Cohesion is an attraction between molecules of the same substance.

End Show 2-2 Properties of Water Slide 8 of 44 Copyright Pearson Prentice Hall The Water Molecule Water's cohesion causes molecules on the surface of water to be drawn inward, which is why drops of water form beads on a smooth surface. Cohesion also explains why some insects and spiders can walk on a pond's surface.

End Show 2-2 Properties of Water Slide 9 of 44 Copyright Pearson Prentice Hall The Water Molecule Adhesion is an attraction between molecules of different substances. Capillary action only occurs when the adhesive forces are stronger than the cohesive forces.

End Show 2-2 Properties of Water Slide 10 of 44 Copyright Pearson Prentice Hall The Water Molecule Adhesion between water and glass causes water to rise in a narrow tube against the force of gravity. This effect is called capillary action.

End Show 2-2 Properties of Water Slide 11 of 44 Copyright Pearson Prentice Hall The Water Molecule Capillary action is one of the forces that draw water out of the roots of a plant and up into its stems and leaves.

End Show 2-2 Properties of Water Slide 12 of 44 Copyright Pearson Prentice Hall The Properties of Water Water expands when it freezes – causing erosion, weathering and formation of soil Water is less dense when frozen – allowing ice to float on the top of lakes and ponds so that living things are still able to survive underneath. Water resists temperature changes – aiding in homeostasis

End Show 2-2 Properties of Water Slide 13 of 44 Copyright Pearson Prentice Hall Solutions and Suspensions A mixture is a material composed of two or more elements or compounds that are physically mixed but not chemically combined.

End Show 2-2 Properties of Water Slide 14 of 44 Copyright Pearson Prentice Hall Solutions and Suspensions Two types of mixtures can be made with water solutions suspensions

End Show 2-2 Properties of Water Slide 15 of 44 Copyright Pearson Prentice Hall Solutions and Suspensions Solutions All the components of a solution are evenly distributed throughout the solution. In a salt–water solution, table salt is the solute—the substance that is dissolved. Water is the solvent—the substance in which the solute dissolves.

End Show 2-2 Properties of Water Slide 16 of 44 Copyright Pearson Prentice Hall Solutions and Suspensions When a crystal of table salt is placed in warm water, sodium and chloride ions are attracted to the polar water molecules. Na + Cl - Water

End Show 2-2 Properties of Water Slide 17 of 44 Copyright Pearson Prentice Hall Solutions and Suspensions Ions break away from the crystal and are surrounded by water molecules. Na + Cl - Water

End Show 2-2 Properties of Water Slide 18 of 44 Copyright Pearson Prentice Hall Solutions and Suspensions The ions gradually become dispersed in the water, forming a solution. Na + Cl - Water

End Show 2-2 Properties of Water Slide 19 of 44 Copyright Pearson Prentice Hall Solutions and Suspensions Water's polarity gives it the ability to dissolve both ionic compounds and other polar molecules, such as sugar. Water is the greatest solvent on Earth.

End Show 2-2 Properties of Water Slide 20 of 44 Copyright Pearson Prentice Hall Solutions and Suspensions Suspensions Some materials do not dissolve when placed in water but separate into pieces so small that they do not settle out.

End Show 2-2 Properties of Water Slide 21 of 44 Copyright Pearson Prentice Hall Solutions and Suspensions The movement of water molecules keeps the small particles suspended. Such mixtures of water and nondissolved material are known as suspensions.

End Show 2-2 Properties of Water Slide 22 of 44 Copyright Pearson Prentice Hall Solutions and Suspensions Some of the most important biological fluids are both solutions and suspensions. The blood that circulates through your body is mostly water, which contains many dissolved compounds. Blood also contains cells and other undissolved particles that remain in suspension as the blood moves through the body.

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