Where Does Water Come From?
What is an atom?
• Simplest part of an
element.
• Protons = + charges
• Neutrons = no charge
• Electrons = - charge
Atoms form molecules by bonding covalently.
Hydrogen and Oxygen atoms covalently bond to form
a water molecule.
Properties of Water
Molecular Structure & Polarity
• Water is a "polar" molecule, meaning that there
is an uneven distribution of electrons resulting
in a molecule with a both a positively and
negatively charged region.
• In other words, the electrons are not shared
equally.
Covalent Bond
NEXT
Hydrogen Bond
• Positive charges on
one molecule and
negative charges on
another molecule
attract each other and
form hydrogen bonds.
View the video on Polarity and H
Bonding!
• Click on the bucket of water below to watch
the short animation on water.
Click on “NEXT” when you are finished.
NEXT
Cohesion
• Due to water’s
polarity, water
molecules stick to
each other forming
hydrogen bonds!
Adhesion
• Due to polarity, water
sticks to other surfaces
as well (unlike
substances, opposites
attract).
Meniscus
Capillary action/Low Viscosity
• Due to polarity, water
is able to move
through small spaces,
against gravity.
• Cohesion and
adhesion are also seen
in this property.
• This helps move water
to the tops of tall trees
and through veins in
humans.
Surface tension
• Due to polarity,
hydrogen bonds form
at the surface of water,
forming an “elastic
film”.
• Things that are light
enough like water
bugs can live and exist
in an ecosystem on top
of the water.
Density
• Unlike most substances,
water becomes less dense
when it freezes.
• H bonds first condense
when water is cold but
then expands when water
freezes leaving air pockets
between the water
molecules.
• Ice floating acts as an
insulator to water in a
body of water so fish
don’t die in the winter.
Density
•Cold water is more dense then hot water.
•Cold water sinks (H bonds condense)
•Hot water floats (H bonds expand)
•Cause of currents in ocean; different life
found at bottom of ocean compared to top.
Solubility/Universal Solvent
• Because of water’s polarity, it is a universal
solvent (can dissolve many things)
• Solute is the material being dissolved in a
solution.
Animation of a solution forming
Due to polarity, water’s opposite charges attract to the opposite
charged ions in salt.
Dissolving (solvent and solute
forms a solution)
• The slight positively charged areas of the water,
surround the Cl- parts of the salt.
• The slight negatively charged areas of the water,
surround the Na+ parts of the salt.
• This property aides in the process of digestion.
High Specific Heat Capacity
(Temperature Moderation)
• Water takes a long time to heat
up and cool down.
• This is because heat energy is
first used to break H bonds,
leaving less heat energy to
increase movement of the
molecules which is necessary to
increase temperature.
• This property helps maintain
homeostasis (body temperature)
and prevents bodies of water
form changing drastically,
effect life in it.
pH (potential hydrogen)
• Solutions are either an acid (below 7), base
(above 7) or neutral (7).
• Due to the dissociation of water, H2O can break
apart in a solution and become H+ (making a
solution acidic) or OH- (making a solution basic)
• If there is an equal amount of each ion, the
solution is neutral.
• Water being neutral
prevents tissue from
being damaged in living
things.