A water molecule (H2O)consist of 3
atoms: 2
atoms and 1
atom.
H
H
Water molecules have a slightly negative (-)
charge near the oxygen atom and a slightly
positive (+) charge near the hydrogen atoms. This
uneven distribution of charges across the water
molecule makes it
.
The opposite poles of the water molecule attract each
other and stick together.
This property allows water to
have so many unique properties!
Water molecules act like a “magnet”
Water is attracted to itself!
happens when a force of
attraction acts on the molecules at the surface
of a liquid. Each water molecule is pulled in all
directions by other molecules. The attractive
forces are pulling downward and sideways
causing the molecules at the surface to be held
more tightly together forming a “skin” at the
surface.
is the tendency of water to stick to other
substances.
Think of it this way... Adhesion is an attraction
between two different substances.
Meniscus
Adhesion causes a
meniscus
• Water sticks to the sides
of the glass
Concave and Convex
• A – concave
• B – convex
Cohesive Properties
• Water sticks to water
causing big droplets to
‘bead’ up
Adhesive Properties
• The
formula
reduces the ability of
adhesion, causing the
water to quickly slide off
windshield
is the measure of mass per unit volume of a substance.
= m/v
changes with temperature. Cold water is denser than
warm water. If combined, the cold water would sink to the bottom
of the warm water.
will change with physical state of matter. Ice is less
dense than water. That means ice will float in water because ice
expands when it freezes causing it to have a greater volume.
•Water has a
of 1 g/mL.
is the ability of a fluid to exert an upward force on an
object that is immersed in the fluid. In other words…
is the ability for an object to float in a fluid!
•All liquids exert an upward force, called buoyant force. If the
buoyant force on an object is greater than the downward force
(gravitational force), the object will float.
So based on buoyant force, how does
a submarine work?
USS Sealey
is the amount of energy that is needed to raise 1
gram of a substance by 1 °C.
Water has a high
(4.184 J/kg∙°C ). This is due to the
strong attraction among water molecules. What does this mean?
Water takes a long time to heat up and to cool down. Water
resists temperature change.
This property enables lakes, streams, and ocean ecosystems to
maintain a stable temperature, even if the air temperature
surrounding the body of water changes drastically.
is the combined forces of
attraction among water molecules and the
molecules of surrounding materials.
Water molecules will “tow” each other along
while in a tube.
This property allows :
•water to move through materials with pores
inside
•causes water molecules to cling to fibers in
materials such as paper and cloth
• water to rise in a straw/tube.
Water is the
. Water dissolves more
substances than any other known substance. A solvent is the
substance in which another substance (solute) dissolves.
Water’s polarity is the reason why water is such a good solvent.
WHY?
Water attracts and bonds with the ions in compounds. As you can
see in the diagram, water molecules attract and forms bonds with
the Na+ and Cl- ions in a crystal of salt. As the water pulls these
ions into solution, the salt crystals dissolves.