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Surface Tension, Capillary Action, and Viscosity

SECTION 10 - Liquids Solids and Intermolecular Forces

Water is the most abundant liquid on earth.  It's a fluid.  Liquids vary greatly in three main areas:

  • Surface Tension
  • Their ability to exhibit Capillary Action
  • Viscosity

Let's take a closer look at each of these 3 listings...


Surface Tension

Surface Tension  =  the resistance of a liquid to an increase in its surface area.

ex:  water "beading" on the waxy hood of a car.

H2O molecules prefer to interact with each other, while minimizing interactions with the car's hood.  See here:

Surface Tension of Water

As mentioned above, liquids with large intermolecular forces will have high surface tensions.

Polar molecules, such as water, thus have high surface tensions.


Capillary Action

Capillary Action  =  the spontaneous rising of a liquid in a narrow tube.

And here's a second definition,

Capillary Action  =  the ability of a liquid to flow against gravity up a narrow tube due to adhesive and cohesive forces.

➞  cohesive forces = the intermolecular forces (IMF) among the molecules in the liquid.

➞  adhesive forces = the attractive forces between the molecules of the liquid and the surface of the tube.



Viscosity  =  the resistance of a liquid to "flowing" because of strong intermolecular forces.

ex:  maple syrup is very viscous.

Viscosity is greater in substances with stronger intermolecular forces because the molecules are more strongly attracted to each other, preventing them from freely flowing around each other.



That's it for liquids.  Now let's move into solids.



There are 2 broad types of solids:

➞  Amorphous Solids  =  considerable disorder in their structure; the solid "looks" inconsistent and irregular at the microscopic level.

       ex:  glass, plastics

➞  Crystalline Solids  =  most abundant by far;  these are solids in which the atoms, molecules or ions are arranged into highly regular and repeating patterns; they are very ordered"Crystals".


Stick around for my next video blog post from SECTION 10 - Liquids, Solids, and Intermolecular Forces. 

We'll go into detail on Crystalline Solids, Types of Unit Cells, FCC Unit Cells, and BCC Unit Cells...