Unit 2

Question 1

polar molecule

Answer 1

a molecule that’s overall charge is unevenly distributed

Question 2

polarity of molecules

Answer 2

oxygen part is slightly negative, hydrogens are slightly positive

• allows water particles to be held together by hydrogen bonds
• high surface tension

Question 3

Properties of Water

Answer 3

• Polar
• Cohesion of Water Molecules
• Moderation of Temperature
• high specific heat
• high heat of vaporization
• Ice less dense than liquid

Question 4

Cohesion

Answer 4

linking together of molecules of the same substance by hydrogen bonds

Question 5

Cohesion of Water Molecules

Answer 5

• along with adhesion allows water to be transported against gravity in plant
• great surface tension

Question 6

Surface tension

Answer 6

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

Question 7

Heat

Answer 7

a measure of the matter’s total kinetic energy due to motions of its molecules
-depends on volume

Question 8

Temperature

Answer 8

measure of heat intensity that represents the average kinetic energy of molecules

Question 9

calorie

Answer 9

the amount of heat it takes to raise the temp of 1g of water 1 degree Celsius .

Question 10

specific heat

Answer 10

the amount of heat that must be absorbed or lost for 1g of that substance to change 1 degree Celsius

Question 11

Water’s high specific heat

Answer 11

• water’s temp will change less when it absorbs or loses heat
• high because hydrogen bonds are first formed or broken by energy before the kinetic energy of the molecules are affected
• keeps temp fluctuations on land and water within limits that permit life
• allows organisms (who are made up mostly of water) to resist changes in their own temp

Question 12

Heat of Vaporization

Answer 12

the quantity of heat a liquid must absorb for 1g of it to be converted from liquid to gas
-water high level: helps moderate Earth’s climate

Question 13

evaporative cooling

Answer 13

as a liquid evaporates, the surface of remaining liquid cools (hottest molecules evaporate)

• contributes to stable temps in lakes and ponds
• prevents terrestrial organisms from overheating (evaporation from leaves, sweat)

Question 14

Floating of Ice on Liquid water

Answer 14

• one of few substances that are less dense as a solid than a liquid
• ice molecules each hydrogen bonded to 4 neighbors in spacious crystal
• ice insulates liquid water below, preventing it from freezing and allowing life to exist under the surface
• provides solid habitat for some animals

Question 15

aqueous solution

Answer 15

a solution in which water is the solvent

Question 16

hydration shell

Answer 16

water molecules surround dissolved ions forming a sphere

Question 17

hydrophilic

Answer 17

any substance that has an affinity for water

Question 18

colloid

Answer 18

a stable suspension of fine particles in a liquid

Question 19

hydrophobic

Answer 19

substances that are non-ionic and non polar and seem to repel water

Question 20

molecular mass

Answer 20

sum of the masses of all atoms in a molecule

Question 21

mole

Answer 21

equal to the molecular mass, the amount of a substance that contains 6.02x10^23 molecules

Question 22

molarity

Answer 22

the number of moles of solute per liter of solution

Question 23

hydrogen ion

Answer 23

H+ a single proton with charge of 1+

Question 24

hydroxide ion

Answer 24

OH- charge of -1

Question 25

hydronium ion

Answer 25

H3O+ represents by H+

Question 26

acid

Answer 26

a substance that increases the hydrogen ion concentration of a solution

Question 27

acidic solution

Answer 27

a solution that has more H+ than OH-

Question 28

base

Answer 28

a substance that reduces the hydrogen ion concentration of a solution

Question 29

basic solution

Answer 29

more OH- than H+

Question 30

The PH scale

Answer 30

-at room temperature 25 C:
- [H+][OH-]= 10^-14
pH= -log[H+}
- less than 7 equals acid 7= neutral greater than 7 basic

Question 31

Buffers

Answer 31

a substance that minimizes changes in the concentrations of H+ and OH- in a solution

• accepts excess H+ or donates H= when developed from a solution
• carbonic acid (H2CO2) is one found in blood
• often acid base pairs

Question 32

ocean acidification

Answer 32

occurs when CO2 dissolves in seawater, reacts and forms carbonic acid, lower pH
-limits calcification (which is important for coral reefs)

Question 33

acid precipitation

Answer 33

refers to rain, snow, or fog with a pH lower than 5.2

Question 34

carbon

Answer 34

has 4 valence electrons and shares these electrons to get 8 valence electrons

• when 4 single bonds are formed the molecule forms a tetrahedral shape
• two carbons that have a double bond form a flat rectangular shape

Question 35

organic molecules

Answer 35

made up mostly of carbon, hydrogen, oxygen, and nitrogen

Question 36

Carbon skeletons can vary in;

Answer 36

length, branching, double bond position, presence of rings

Question 37

hydrocarbons

Answer 37

organic molecules consisting of only carbon and hydrogen

• major components of petroleum
• many of cells organic molecules have regions of hydrocarbons, ex. fat molecules tails
• relatively nonpolar, often behave hydrophobically
• can undergo reactions that release large amounts of energy

Question 38

Isomers

Answer 38

compounds that have the same number of atoms of the same elements but different structures and thus different properties

Question 39

structural isomers

Answer 39

differ in the covalent arrangements of their atoms and the location of double bonds

Question 40

cis-trans isomers

Answer 40

carbons have covalent bonds to the same atoms but these atoms differ in their spatial arrangement due to the inflexibility of double bonds

• cis isomer; both x atoms on the same side of the double axis
• trans isomer; x’s on opposite sides

Question 41

Enantiomers

Answer 41

isomers that are mirror images of each other and that differ in shape due to the presence of an asymmetric carbon
-can cause drugs to have different effects

Question 42

asymmetric carbon

Answer 42

a carbon that is attached to four different atoms.