WATER AND LIFE

Water contains ______ bonds and is a ______ molecule

Polar covalent, polar

Polar Covalent bond

A covalent bond in which electrons are shared unequally between two atoms of different electronegativity

Polar molecule

A molecule that has an asymmetrical distribution of charge (two oppositely charged ends)

______ bonds form between water molecules

Hydrogen

A hydrogen bond is weaker than covalent and ionic bonds but _______ than other intermolecular forces

Stronger

Hydrogen bonds are responsible for the unique properties of water

Cohesive behavior, ability to moderate temperature, expansion upon freezing, and versatility as a solvent

Cohesion

The sticking together of particles of the same substance, often by hydrogen bonds

Cohesion is responsible for what?

Water’s high surface tension

Surface tension

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

Adhesion

The sticking together of particles of different substances, often by hydrogen bonds

Cohesion and adhesion are responsible for the transport of ______ in plants

Water

All particles of matter are?

In constant motion and have kinetic energy

Kinetic energy

The energy of motion

Temperature

Measures the average kinetic energy of the particles in a sample of matter

Which property of water has the strongest intermolecular forces

Solids

Which property of water has the weakest intermolecular forces?

Gas

As kinetic energy increases

Temperature increases

Heat energy

The flow of thermal energy from a warmer object to a cooler object

As an object absorbs heat energy…

The average kinetic energy of its particles (aka temperature) increases

During a phase change, the absorbed heat energy is used to

Break the intermolecular forces

During melting and vaporization, what is happening to temperature and KE

Stays the same

Water has a HIGH SPECIFIC HEAT

because of strong hydrogen bonds

Specific heat

The amount of heat that must be absorbed or lost for 1g of the substance to change its temperature by 1 degree celcius

A sample of water must absorb or release

A lot of energy for the temperature to change

A large body of water can absorb and change a huge amount of heat

With only a slight change in its own temperature

Water _________ by absorbing heat from warmer air and releasing stored heat into cooler air

Moderates air temperature

Due to the high specific heat if the ocean, coastal area have what in comparison to inland areas

Cooler summers and warmer winters (moderate climates)

Water has a ______

HIGH HEAT OF VAPORIZATION

Vaporization

When liquid particles become gas particles

Evaporation

Only liquid particles at the surface of a sample can become gas particles

Boiling

Liquid particles throughout the sample can become gas particles

Heat of vaporization

The amount of heat that must be absorbed for 1g of the substance to be converted from the liquid to the gaseous state

Evaporative cooling

The process in which the surface of an object becomes cooler during evaporation

The molecules with the greatest kinetic energy ______

Evaporate

The molecules left on the surface ______

Have lower kinetic energy

The average KE or temperature of the surface _____

Decreases

Water moderates __________ by evaporative cooling

Surface temperature

Density

The degree of compactness of a substance

As distance between particles increases,

Density decreases

Ice is _______ dense than liquid water

Less

Solute

A dissolved substance

Solvent

A substance that can dissolve another substance

Solution

A mixture in which particles of one substance are spread uniformly throughout a second substance

Aqueous solution

A solution in which water is the solvent

Hydrophilic substance

“Water-loving” substance

Two properties of hydrophilic substances

Polar molecules, ions, and ionic compounds and are soluble in water

Hydrophobic substance

“Water-fearing” substance

Two properties of hydrophobic substances

Non polar molecules and are insoluble in water

Acid

A substance that donates a hydrogen ion

Base

A substance that accepts a hydrogen ion

pH scale measures what of a solution

The hydrogen ion concentration

As the hydrogen ion concentration increases, pH

Decreases

Each change of a single pH unit signifies a ______ change in the H+

Tenfold

A solution at pH 4 has ______ times more H+ ions than a solution at pH 5

10

A solution at pH 3 has _____ times more H+ ions than a solution at pH 5

100