Bio - A1.1 - Water (copy)

why is water important to life?

• Provides a medium for enzymes to dissolve and work

• Provides a hemically stable medium for life processes to operate

why are covalent bonds in water polar?

Due to unequal sharing of electrons

Why do hydrogen bonds form?

Due to polarity of water molecules

What is cohesion?

The force by which individual molecules of the same type attract and associate

Describe Surface Tension

• The outermost molecules of water form hydrogen bonds with water molecules below them

• Since there are no neighbouring molecules above the surface of water, they exhibit stronger forces of attraction with the H2O molecules below them.

• The net inward force causes molecules on the surface to contract and resist being stretched or broken

• This is surface tension.

How do properties of water allow water stridrs to inhabit the surface of water?

• Surface tension allows molecules on the surface to contract and resist being stretched or broken

• The mass of water striders are not great enough to break the surface tension

• Waxy cuticle prevents the insect from getting wet

Outline the effects of water on molecule polarity

• Molecule polarity of water leads to the formation of weaker hydrogen bonds

• Hydrogen bonds are largely responsible for the unique properties of water

• These include cohesion, adhesion, viscosity