If it weren't for the fact that the TV set and the refrigerator are so far apart, some of us wouldn't get any exercise at all. Joey Adams Joey Adams
WATER THE MAGIC MOLECULE
WATER IS FORMED WHEN HYDROGEN AND OXYGEN SHARE ELECTRONS. H O H
WATER IS A POLAR MOLECULE.THIS MEANS THAT THE ELECTRONS ARE NOT SHARED THE SAME WAY. OXYGEN GETS A BIGGER SHARE, SO IT HAS A SLIGHT NEGATIVE CHARGE. THE HYDROGENS HAVE A SMALLER SHARE, SO THEY HAVE A SLIGHT POSITIVE CHARGE. H O H 22
WHAT THIS MEANS IS THAT WHEN YOU PUT A BUNCH OF WATER MOLECULES TOGETHER, THE POSITIVE ENDS OF ONE WILL BE ATTRACTED TO THE NEGATIVE ENDS OF OTHERS. THIS IS LIKE A GLUE THAT HOLDS THE MOLECULES CLOSER TOGETHER THAN WOULD BE THE CASE IF THEY DID NOT HAVE THE CHARGES. THIS “STICKEYNESS” GIVES WATER SOME UNUSUAL PROPERTIES.
WE CALL MOLECULES THAT HAVE NEGATIVE ENDS AND POSITIVE ENDS POLAR MOLECULES. COMPOUNDS THAT ARE BUILT OF POLAR MOLECULES HAVE ADDITIONAL ATTRACTIONS BETWEEN THE MOLECULES THAT OTHER COMPOUNDS DON’T. WATER HAS A VERY LOW MASS, BUT IT HAS A VERY HIGH FREEZING POINT AND BOILING POING FOR SUCH A LIGHT MOLECULE. Melting Point Boiling Point Water O o C100 o C Methane -184 o C-162 o C
Water molecules
OTHER UNUSUAL PROPERTIES OF WATER: 1. HIGH HEAT OF FUSION (heat to melt) 2. HIGH HEAT OF VAPORIZATION (heat to boil) 3. HIGH SURFACE TENSION 4. SOLID IS LESS DENSE (ICE FLOATS) 5. WATER DISSOLVES OTHER POLAR MOLECULES AND SALTS
SURFACE TENSION IS DUE TO UNEQUAL FORCES AT THE SURFACE OF WATER. THERE ARE NO MOLECULES ABOVE THE SURFACE, SO ALL OF THE FORCES ARE DIRECTED TO THE SIDES AND DOWN.
IT IS THIS UNBALANCE OF FORCES AT THE SURFACE THAT MAKES WATER DROPLETS SPHERICAL. BECAUSE OF THIS UNBALANCE OF FORCES AT THE SURFACE, YOU ALSO HAVE TO USE ENERGY TO EXPAND THE SURFACE OF WATER. THIS MAKES IT POSSIBLE FOR WATER STRIDERS TO WALK ON WATER.
THIS UNBALANCE OF FORCES AT THE SURFACE ALSO MEANS THAT WATER WILL RISE IN A CAPILLARY TUBE. THIS SAME EFFECT IS WHAT CAUSES WATER TO RISE IF YOU DIP THE END OF A PAPER TOWEL IN WATER.
ARRANGEMENT OF WATER MOLECULES IN ICE
Water molecules in ice
WATER EXISTS IN ALL THREE PHYSICAL STATES IN NATURE: 1. SOLID 2. LIQUID 3. VAPOR (GAS)
IF YOU HEAT ICE, THE TEMPERATURE WILL RISE TO THE MELTING POINT. AT THAT POINT, THE MOLECULES GET ENOUGH ENERGY TO BREAK SOME OF THE POLAR BONDS BETWEEN THEM. THE WATER BECOMES MORE FLUID, AND MELTING OCCURS. AS YOU CONTINUE TO ADD ENERGY, THE MOLECULES GAIN ENERGY AND MOVE FASTER RELATIVE TO EACH OTHER. EVENTUALLY, YOU REACH THE BOILING POINT, AND THE MOLECULES HAVE ENOUGH ENERGY TO COMPLETELY SEPARATE AND BECOME GAS. BOILING OCCURS.
iceberg SOLID AND LIQUID WATER
ICEBERG ABOVE AND BELOW WATER