Simulations & Videos for

Lesson 5.2: Surface Tension

Accompanying Lesson Plan: Lesson 5.2: Surface Tension

Youtube ID: wuEOroGyHJc

Water’s Surface Tension

  • The paper clip is on the water but is not floating like a boat which is less dense than water.
  • The paper clip is more dense than water but can rest on the surface of the water because of the water's surface tension.

Water Strider and Water Molecules

  • Evidence of water's surface tension can be seen where the water strider's legs dent but do not break through the water's surface.
  • The attraction of polar water molecules to each other helps create water's strong surface tension.

Why Water Beads

  • The water molecules beneath the surface are pulled in all directions.
  • The molecules at the surface are pulled together and in.
  • This creates a tighter arrangement of molecules at the surface and the round shape of a drop of water.

Water and Alcohol Molecules

  • Alcohol has one O–H bond which is polar, but a large portion of the molecule is made up of C–H bonds which are nonpolar.
  • Alcohol molecules do not attract each other as strongly as water molecules and have a weaker surface tension.

Water and Detergent

  • The charged end of a detergent molecule attracts water molecules at the surface in an outward direction.
  • This disrupts the way the molecules normally attract at the surface and weakens the surface tension, causing the drop to collapse.

Youtube ID: JOi0VLrKeWM

Water on Paper Towel

  • Paper is made from cellulose which is made of glucose molecules bonded together.
  • Glucose has many O–H bonds which are polar.
  • Polar water molecules are attracted to the polar cellulose and cling to it.

Youtube ID: mmI2TerXlrY

Water on Wax Paper

  • Wax is made of paraffin which is only carbon-hydrogen bonds.
  • C–H bonds are not polar.
  • Water is more attracted to itself than to the wax so it stays together and does not spread out or absorb into the wax paper.