the chemistry of life properties of water. the water molecule polarity –polar molecules have a...
DESCRIPTION
Hydrogen Bonds Polar water molecules act like magnets and attract each other Hydrogen Bonds –The attraction of the Hydrogen end (+) of one molecule for the Oxygen end (-) of another water molecule.TRANSCRIPT
The Chemistry of Life
Properties of Water
The Water MoleculeThe Water Molecule• Polarity
– Polar molecules have a region with a slight positive charge and a slight negative charge.
– A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms.
• Oxygen has 8 protons and a larger pull on the electrons than Hydrogen with just 1 proton.
Hydrogen BondsHydrogen Bonds• Polar water molecules act like
magnets and attract each other • Hydrogen Bonds
– The attraction of the Hydrogen end (+) of one molecule for the Oxygen end (-) of another water molecule.
Hydrogen BondsHydrogen Bonds
CohesionCohesion• The attraction
between molecules of the same substance (e.g. water).
• Allows some insects and spiders to walk on water.
AdhesionAdhesion• Attraction between molecules of
different substances• Responsible for Capillary forces
in plants
Solutions & Solutions & SuspensionsSuspensions
• Water is usually part of a mixture.
• There are two types of mixtures:–Solutions–Suspensions
SolutionSolution• Made of a solute and solvent.• Ionic compounds disperse as ions in
water (NaCl becomes Na+ Cl-)• Evenly distributed• SOLUTE
– Substance that is being dissolved• SOLVENT
– Substance into which the solute dissolves
SolutionSolution
SuspensionsSuspensions• Substances that
don’t dissolve but separate into tiny pieces.
• Water keeps the pieces suspended so they don’t settle out.
Acids, Bases & pHAcids, Bases & pH• 1 water molecule in 550 million
naturally dissociates into a Hydrogen Ion and a Hydroxide Ion
Hydrondium Ion Hydroxide Ion Acid Base
H2O H+ + OH-
The pH ScaleThe pH Scale• Indicates the concentration of H+ ions• Ranges from 0 – 14• pH of 7 is neutral• pH 0 – 6.99 is acid … H+ • pH 7.01 – 14 is basic… OH- • Each pH unit represents a factor of
10 change in concentration
AcidsAcids• Strong Acid
= pH 1-3 H+ ions
BasesBases• Strong Base
= pH 11 – 14 OH-
ions
BuffersBuffers• Weak acids or bases that react
with strong acids or bases to prevent sharp, sudden changes in pH.
Weak Acid Weak Base
