PROPERTIES OF WATER

Water: A Most Important Substance Life as we know it would not exist without water. Compared to other compounds and minerals, water has extraordinarily unique properties. It does things (things that support life) that other substances don’t.

Structure of Water 2H2 + O2  2H2O H2O What makes water? What does this mean? Simply put, hydrogen (H) and oxygen (O) combine to make water (H2O) A single water molecule is a compound made of two hydrogens and one oxygen. H2O

Structure of Water + + + + Water is polar, meaning one side is positively (+) charged and the other side is negative (-). + + + + ▬ ▬ Because Oxygen is bigger, it “hogs” more electrons. Thus, the Oxygen side of water tends to be negative (-), and the Hydrogen side positive (+).

Water is a Polar Molecule -has oppositely charged ends Water consists of one oxygen atom bound to two hydrogen atoms by two single covalent bonds. Oxygen has unpaired & paired electrons which gives it a slightly negative charge while Hydrogen has no unpaired electrons and shares all others with Oxygen Leaves molecule with positively and negative charged ends (like a magnet)

WATER’S POLARITY AND HYDROGEN BONDS

Water’s Properties Cohesion Adhesion Capillary Action Solid water (ice) is less dense than liquid Solvent

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

COHESIVE PROPERTY

http://www.youtube.com/watch?v=A042J0IDQK4

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

ADHESIVE PROPERTY

water evaporates from leaves = transpiration Capillary action water evaporates from leaves = transpiration All thanks to hydrogen bonding! adhesion, cohesion and capillary action water taken up by roots

Water Cells are about 70-95% water. Three-quarters of Earth’s surface is submerged in water. Water is the only common substance to exist in all three physical states of matter solid, liquid and gas

STATES OF WATER

WATER AS A GAS

WATER AS A LIQUID

WATER AS A SOLID

Solid water (ice) is less dense than liquid Ice is less dense than water: the molecules are spread out to their maximum distance Density = mass/volume same mass but a larger volume

SOLUTIONS: Water is the “universal solvent” Solute: Substance that is dissolved (Salt NaCl) Solvent: Substance in which the solute dissolves (Water) Polarity makes water a great solvent!!!!!!!!!!!!!!!!!!!!!!!!!! What other solutions could be made using water?

pH Scale

THE END