Physical Properties of Water

* Water statistics Covers 75% of Earth’s surface (why understanding it is important!) Covers 75% of Earth’s surface 97% oceans 3% freshwater 2% (of Total) in ice caps and glaciers 1% in lakes, underground, or in atmosphere (usable by humans) Makes up 70% of the human body 92% of blood plasma 80% of muscle tissues 60% of red blood cells

Physical properties Water: “H2O” = Two Hydrogens(H) and one Oxygen(O) in every water molecule Is clear, colorless, odorless, and tasteless * Colors, tastes and odors are caused by substances dissolved in the water. Boils at 100°C Freezes at 0°C Density = 1.0 g/mL (at 4°C) Water is a Polar Molecule

Polarity of Water In a water molecule two hydrogen atoms form a POLAR bond with an oxygen atom. Gives water more structure than other liquids The Oxygen side of water is negative The Hydrogen side of water is positive 2 corners are orbitals with unshared electrons and a weak negative charge 2 are occupied by hydrogen atoms that have polar covalent bonds http://www.physicalgeography.net/fundamentals/images/water.JPG

Water has a variety of unusual properties because of attractions between positive and negative charges. (Like magnets) The slightly negative regions of one water molecule are attracted to the slightly positive regions of nearby molecules, forming a hydrogen bond. A water molecule is a polar molecule because opposite ends of the molecule have opposite charges. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

- - - - - - - - + + + + + + + + Water molecules are: Bent (or V-shaped) O H + - O H + - Polar: have an uneven distribution of e- (electrons) A partial (less than +1) positive charge by the H’s A partial (< –1) negative charge by the O O H + - O H + - O H + - Attracted to each other: (+) and (-) charges of one H2O are attracted to other (+) and (-) of another H2O These attractions are called hydrogen bonds (“H bonds”); occur between H2O molecules O H + - O H + - O H + -

How did water get those Positive and Negative charges? Let’s investigate: Paste your water molecule in the space below and answer the questions provided