Properties of Water: Polarity The oxygen and hydrogen atoms in water share electrons unequally (a polar covalent bond). This happens because the oxygen atom has a higher attraction for the shared electrons. The result is a slight negative charge on the oxygen atom and slight positive charge on the hydrogen atoms.

Properties of Water: Polarity 1.What type of bond does the oxygen and hydrogen atoms of water have? 2.Oxygen has what type of charge? 3.Hydrogen has what type of charge?

Properties of Water: Polarity *Water’s polarity results in hydrogen bonding *The polar water molecules are held together by hydrogen bonds *The partial positive charge on the hydrogen of one molecule is attracted to the partial negative charge on the oxygen of another molecule *Each water molecule can form a maximum of four hydrogen bonds with neighboring water molecules *Water has unique properties because of its polarity and hydrogen bonding; these include: 1. Cohesion3. Moderation of temperatures 3. Expansion upon freezing4. Versatility as a solvent

Properties of Water: Polarity 4.Polar molecules of water are held together by what type of bond? 5.Each water molecule can form a maximum of _____ hydrogen bonds with neighboring water molecules. 6.What are the four properties of water because of its polarity?

Hydrogen Bonding

Properties of Water: Cohesion Cohesion occurs when a substance is held together by hydrogen bonds *Cohesion causes water molecules to stick together *Cohesion contributes to the upward movement of water in plants by holding the water column together Adhesion occurs when water is attracted to other substances. This is what causes the meniscus in a graduated cylinder! Surface Tension is a measure of how difficult it is to stretch or break the surface of a liquid *Water has a greater surface tension than most liquids *This causes water to bead

Cohesion

Adhesion

Surface Tension

Properties of Water: COHESION 7.Define Cohesion 8.Give an example of Cohesion 9.Define Adhesion 10.Define Surface Tension 11.Give an example of Surface Tension

Properties of Water: Moderating Temperatures *Breaking hydrogen bonds causes the temperature of water to rise slower when it is heated (compared to other liquids) *This also causes water to vaporize slower *Forming hydrogen bonds also causes the temperature of water to lower more slowly when cooled

Properties of Water: Moderating Temperature 12. What causes water to vaporize slower and causes it to cool off slower?

Properties of Water: Ice is Less Dense Than Liquid Water *Hydrogen bonds give ice a stable, 3- dimensional structure *A given volume of ice has fewer water molecules than the same volume of liquid water (so it is less dense and ice floats) *Water is most dense at 4 0 C

Properties of Water: Ice is Less Dense Than Liquid Water 13.What gives ice its stable 3-D Structure? 14.Why does ice float in water? 15.When is water most dense?

Properties of Water: Universal Solvent Because water is polar, it forms solutions with a wide variety of other covalently bonded or polar compounds, and with the charged ions of ionically bonded compounds (it dissolves “like” substances)

Properties of Water: Universal Solvent 16.Using the internet…explain what makes water dissolve “like” substances so well. NOTE: REREAD THE PASSAGE ON THE PREVIOUS SLIDE…LOOK IT UP ON THE INTERNET AND EXPLAIN IN YOUR OWN WORDS