A1.1 Water

Cohesion of water molecules

the ability of like molecules to stick together

Cohesion of water molecules: Surface tension

• sticks loose to the molecules next to them (cohesive force)

• must be broken for an object to move past it

Cohesion of water molecules: Xylem transportation

• water moving in a plant, moves through the xylem

• water evaporates from the leaves

• water has cohesiveness to the next water molecule

• tension pulls water up the xylem from the roots

Adhesion of water molecules

water will form intermolecular association with polar and charged molecules

Water forming bonds with other molecules creates

the miniscus and capillary action

Capillary action in soil

• water adheres to the polar molecules in soil

• can be drawn in by root hairs on the roon

Capillary action in xylem

• water in xylem adheres to the sides

• keeps water column from dropping down

• works together with cohesion to pull water from roots to leaves

Hydrophilic molecules

dissolve in water

Hydrophobic molecules

do not dissolve in water

Hydrophilic substances

• substances that dissolve in water

• substances that water adhere to

Hydrophobic molecules

• molecules that do not have a negative or positive charge (non-polar)

• molecules that dissolve in other solvents