AP Biology: Water and its Properties Study Set

H20??? more like H2 HO

what is oxygens atomic number

\

8

what is hydrogens atomic number

1

how many oxygens and how many hydrogens are in a water molecule

1 oxygen and 2 hydrogens

how many valence electrons does oxygen have

6 valence

how many valence electrons does hydrogen have

1 valence

what kind of bond is formed between the oxygen and the hydrogen in a water molecule

covalent bonds

what does covalent mean

the two atoms share electrons (only their valence electrons)

how many bonds are needed to give oxygen an outershell

2 bonds

how many bonds is needed to give hydrogen a full outer shell

1 hydrogen bond is needed

what does it mean when oxygen has a high electronegativitiy

it means the oxygen atom has a big affinity for the electrons in a covalent bond (its an electron hog)

what is meant when it says water molecules are polar

there is a slight negative charge on one side and a slight positive charge on the other side

why do the electrons tend to hang around the oxygen atom in a water molecule

oxygen has a high electronegativity

what happens as a result of the electrons all hanging out near the oxygen

there is now a negative charge on the oxygen side and a positive charge on the hydrogen side due to the imbalance of electrons

what does waters polarity allow it to do?

form weak bonds with other water molecules

what are the weak bonds called that are formed between water molecules?

hydrogen bonds

hydrogen bonding of water is crucial to what?

life on earth

what is the symbol for a partial charge

δ

what is the seperation of charges called

polarity

what does polar covalent mean

the uneven sharing of electrons resulting in a seperation of charges in a molecule

what does cohesion mean

when two of the same molecules form a hydrogen bond

what is an example of cohesion

water forming hydrogen bonds with other water molecules

what is adhesion

when different polar molecules form hydrogen bonds

what is surface tension

it is a result of the cohesion of water molecules at the surface of water

what is surface tension kind of like?

a weak barrier between the air and the water

whats an example of surface tension

paper clip floating on water

what is capillary action

the ability of water to climb small tubes against gravity

what causes capillary action

adhesion

capillary action is caused by the _________ __of water to the side of the tube and by__ _____________ to itself.

adhesion, cohesion

what is an example of cohesion

trees moving water through capillary action

what is specific heat

the amount of energy needed to raise the temperature of a substance by 1 degree celcius

what is heat of vaporization

the energy needed to convert liquid to a gas (to vaporize the liquid)

water has a high _____________

specific heat

how does water and earths temperature relate

the oceans help to regulate earths temperature d

water also helps to do what to our bodies

regulate our temperature

why do desert’s temperatures constantly fluctuating

deserts do not have water to help regulate temperature

what is evaorative cooling

when water absorbs and dissipates heat as it evaporates

when it is humid out, why cant the water from our skin evaporate?

because there is already water in the air

why can water dissolve polar and ionic molecules

the water molecules attatch to the molecules and pull them apart and surrounds the individual molecules

what is it called when a substance is dissolved in water and the water molecules fully surround the atoms

hydration sphere

fats and oils are _______________

hydrophobic (hate water)

what is the density anomaly

when ice is less dense than water

why is ice less dense than water

as the water cools down, the molecules slow down and begin to slightly repel each other, which allows for air to get trapped which makes it less dense

why is floating ice important for life in aquatic ecosystems

floating ice allows for the ice to thaw, preventing the freezing of entire bodies of water

why can life continue in freezing bodies of water q

ice acts as an insulating top layer, which regulates temp of water underneath the ice