1. Why is Water Sticky? Part 1 -- Investigating the Properties of
Cohesion & Surface Tension

2. What are Hydrogen Bonds?
Weak chemical attractions between polar molecules
Polar molecules: have an uneven distribution of electrical charge; one end is positive and the other end is negative (like a battery)
Water molecules are polar
The blue “Mickey Mouse ears” represent Hydrogen atoms (negatively charged)
The red “Mickey Mouse head” represents an Oxygen atom (positively charged)
The blue end of one water molecule is attracted to the red end of another, forming a hydrogen bond

3. What is Cohesion? Since water is polar, it bonds (sticks) to itself
Many water molecules “stick” together to form drops
This is referred to as cohesion
Cohesion: an attraction between substances of the same kind

4. Why can some insects walk on water?
Cohesion causes surface tension
Surface tension: cohesion of water molecules at the surface of a body of water
Due to surface tension, some things can “float” on water
Allows water striders to “skate” across the top of water