Water and life Bio 101

Water

two hydrogen atoms joined to one oxygen atom by polar covalent bonds, weak in liquid form

Polar molecule

The unequal sharing of electrons

Cohesion

the linking of like molecules, often through hydrogen bonds, contributes to the transport of water against gravity in plants

Surface tension

a measure of how difficult it is to stretch or break the surface of a liquid.

Adhesion

the clinging of one substance to another; adhesion of water by hydrogen bonds molecules of the cell wall counters gravity

Kinetic energy

the energy associated with the relative motion of objects

Thermal energy

Kinetic energy due to the random motion of atoms and molecules, dependent of the matters volume

Temperature

a measure in degrees of the average kinetic energy of the atoms and molecules

specific heat

the amount of heat that must be absorbed or lost for 1 gram of substance to change temperature by 1c

Heat of vaporization

the quantity of heat a liquid must absorb for 1 gram to be converted from liquid to gas

Evaporative cooling

the process in which the surface of an object becomes cooler during evaporation; molecules with the most kinetic energy change from liquid to gas

Solution

a homogeneous mixture of two or more substances

Solvent

the dissolving agent

Solute

the substance being dissolved

Aqueous solution

what you get when water is the solvent

hydration shell

water molecules form this around around dissolved ions

hydrophilic

substances that have an affinity to water, typically have partial positive/ negative charges that bond with hydrogen and oxygen in water

hydrophobic

substances that repel water nonionic, non polar substances, cannot form hydrogen bonds.

molecular mass

the sum of the masses of all the atoms in a molecule

mole

the number of grams of a substance that equals its molecular mass in daltons

Molarity

number of moles per liter of solution

acid

substance that increases H+ concentrations in a solution

base

a substance that reduces the H+ concentrations in a solution

Buffers

solutions that contain a weak acid and its corresponding base that minimize changes in ph, this occurs through the exchange of H+