Water Flashcards
What is polarity
A molecule in which the charges are unevenly distributed
Regions of negativity and regions of positivity
What atom has the greater share of electrons in water?
Oxygen has the greater share of electrons in water, therefore it has a slight negative charge. It has a greater pull on the electrons due to a greater proton number
How are hydrogen bonds formed?
Polar molecules interact with each other as the positive and negative regions of each attract each other
What are the bonds within water called?
Intramolecular bonds. Bonds between two molecules of water are intermolecular
Why does water have a high specific heat capacity?
It takes lots of energy to raise water’s temperature as lots of hydrogen bonds must be broken
Why is it advantageous that water has a high shc?
Water acts as a coolant, helping to buffer temperature changes.
Maintains constant temperatures for enzyme action
Provides a stable and constant environment
Ensures that not a lot of water is lost by sweating
What is cohesion?
Attraction between molecules of the same substance- water molecules stick together and move as one column
Eg- how plants draw water up their roots
What is adhesion?
An attraction between molecules of different substances- eg water molecules adhere to the xylem vessel as it is polar
Why is adhesion and cohesion useful?
Allows water to exhibit capillary action (rising up a narrow tube against the force of gravity)
Why does water make a good transport medium/ solvent?
Substances such as glucose, amino acids, CO2 and 02 can dissolve in blood (they are polar and form hydrogen bonds with the water) and be transported around the body.
Water acts as a medium for chemical reactions (it is the cytosol of most cells)
What is a property of hydrogen bonding?
Hydrogen bonds are relatively weak but occur in large numbers.
Define hydrophobic and hydrophilic
Anything that dissolves in water is hydrophilic- it can only dissolve if it is polar because then it can form hydrogen bonds with water
Anything that cannot dissolve in water is hydrophobic- it is not polar and therefore cannot form hydrogen bonds with water.
How is ice different from water?
When water turns to ice, it becomes less dense. The water molecules form hydrogen bonds between each other and arrange themselves into a rigid tetrahedral lattice structure. This causes the molecules in ice to be further apart from each other, when compared to water molecules
How is ice floating beneficial to aquatic organisms
Ice floats and forms on the surface of ponds/lakes which forms an insulating layer for the organisms and prevents the habitat from freezing.
How do organisms inhabit the surface of water?
Water has surface tension- molecules are more strongly attracted to each other than they are to the air meaning organisms can inhabit the surface.
