Properties of Water
Water is a tasteless, odorless, colorless substance that is essential to all forms of life.
Nearly 70% of the Earth is covered with water. It appears in many forms including
clouds, rivers, oceans, lakes, glaciers, rainwater, and groundwater. Water continuously
moves through a cycle of evaporation, condensation, and precipitation.
Water is one of the few substances that naturally occurs on Earth in all three states;
solid, liquid and gas. Solid water is found in the icebergs and glaciers at the Poles.
Liquid water is found in the oceans, lakes, and rivers. Water in the gas state, also
known as water vapor, is found in the atmosphere.
The chemical formula for water is H2O. The water molecule consists of two hydrogen
atoms and one oxygen atom. The hydrogen atoms are attached to one side of the
oxygen atom. The hydrogen end of the molecule has a positive charge and the oxygen
end of the molecule has a negative charge. Since opposite charges attract, water
molecules tend to attract each other, making water kind of “sticky”. The positive end of
one molecule is attracted to the negative end of another molecule. Because a water
molecule has a positive charge on one end and a negative charge on the other end,
water molecules are said to be polar and act like magnets.
Because a water molecule is polar, this causes it to be attracted to other
water molecules and also molecules of other substances. The attraction
between water molecules is called cohesion. Cohesion is why the bubble
gets bigger and bigger on the surface of a penny. The attraction of the water
molecule to other materials like glass or soil is called adhesion. Examples
of adhesion are water sticking to the outside of a soda can or condensation
on a windshield in the morning
If a glass is filled to the brim and more water is added gently, the level of the
water will exceed the top of the glass. Surface tension is a thin layer that
forms on top of water because the water molecules are sticking together.
Strong cohesion between water molecules causes the water surface to behave as
though a thinly stretched coating or skin covers it. Surface tension is like water’s skin.
It forms because water molecules are attracted to one another more at the surface
Surface tension is such a strong force that it can support small paper clips and insects.
Water striders are insects that can literally walk on water because of the bonds between
water molecules.
How is water able to go against gravity and travel up the roots of plants? Capillary
action is the movement of water up a porous material against the force of gravity.
Water is able to travel uphill because water molecules tend to stick together and they
are easily attracted to other surfaces like soil, glass, paper or plant material.
1. List 4 different forms of water on Earth.
___________________________________________________________________
2. Describe how or where each of the 3 states of water can be found on Earth.
Solid - ________________________________________
Liquid - _______________________________________
Gas - ________________________________________
3. Where is the positive end of a water molecule? ____________________________
4. Where is the negative end of a water molecule? ___________________________
5. Water molecules are polar which means they act like ________________________
Define the following:
Cohesion - __________________________________________________________
___________________________________________________________________
Adhesion - ___________________________________________________________
____________________________________________________________________
Surface tension - ______________________________________________________
____________________________________________________________________
Capillary action - _______________________________________________________
_____________________________________________________________________
6. Why is a water molecule a polar molecule?
______________________________________________________________________
7. Plant roots transporting water up to the leaves of a flower is an example of
_________________________________________
8. Water that sticks to the outside of a glass is an example of ____________________
9. Water drops get bigger and bigger because of _____________________________
10. Some insects are able to walk on water because of _________________________
11. What is a water molecule made of?
______________________________________________________________________
12. Why does surface tension form?