Ch 2 - Life Chemistry and Energy

Question 1

pure substance that contains only one kind of atom

Answer 1

element

Question 2

Which elements make up about 96% of all living matter?

Answer 2

Carbon
Hydrogen
Nitrogen
Oxygen

Question 3

What determines how atoms with behave, and whether they will form bonds?

Answer 3

the electrons in the atom’s valence shell

Question 4

Bonds that form when atoms gain or lose one or more electrons to achieve stability.

Answer 4

ionic bonds

Question 5

The strong bonds that form when atoms share electrons.

Answer 5

covalent

Question 6

Groups of atoms that give important properties to biological molecules.

Answer 6

Functional Groups

Question 7

electrically charged particle that forms when an atom gains or loses one or more elections

Answer 7

ion
(cations + charged)
(anions - charged)

Question 8

the attractive force that an atomic nucleus exerts on electrons in a covalent bond

Answer 8

electronegativity

Question 9

if two atoms are close to each other in electronegativity, they will form what type of bond?

Answer 9

nonpolar covalent bond

Question 10

when electrons are drawn to one nucleus more than the other, they will form what type of bond?

Answer 10

polar covalent bond

Question 11

What explains the fact that water molecules are “sticky?”

Answer 11

Hydrogen Bonding

+H is attracted to -O

Question 12

Water characteristic explained by Hydrogen bonding between water molecules.

Answer 12

Cohesion
(water is “sticky”)
(explains “surface tension”)

Question 13

Water characteristic explained by Hydrogen bonding between water molecules and other substances.

Answer 13

Adhesion
(explains capillary action in plants)
(meniscus in graduate cylinder)
(water “climbs” up paper towel)

Question 14

Explain why water makes an excellent solvent.

Answer 14

Polarity
Water is a polar molecule. Polar water molecules surround + and - ions (in Ionic compounds) as well as other polar molecules.

Question 15

Substances that have an attraction to water

Answer 15

hydrophilic

polar molecules

Question 16

Substances that don’t have an attraction to water

Answer 16

hydrophobic

non-polar molecules

Question 17

Why does ice float?

Answer 17

Hydrogen bonding in ice becomes stable, causing water to become less dense than liquid water. (H bonds in liquid water are constantly breaking and reforming)

Question 18

Water characteristic that resists changes in temperature.

Answer 18

High specific heat

water must absorb a lot of energy to break H bonds before it will change temperature!

Question 19

Water characteristic that explains the difficulty in changing liquid water into its gaseous form.

Answer 19

Heat of Vaporization
(water must absorb a lot of energy to break H bonds - it absorbs this energy from its surroundings and thus has a cooling effect on its surroundings)

Question 20

Describes how acidic or basic a solutions is

Answer 20

pH

Question 21

H+ = OH-

Answer 21

neutral solution  
(pH = 7)

Question 22

H+ > OH-

Answer 22

acidic solution

pH < 7

Question 23

H+ < OH-

Answer 23

basic solution

pH > 7

Question 24

Why must the pH of living cells be about 7?

Answer 24

pH affects the shape of molecules - altered pH will affect the function of molecules and therefore affect cellular function

Question 25

chemical reactions that build larger molecules from smaller molecules

Answer 25

dehydration synthesis
(water taken out)
(energy input)
(anabolic reactions)

Question 26

chemical reactions that split larger molecules into smaller molecules

Answer 26

hydrolysis
(water input)
(energy released)
(catabolic reactions)

Question 27

chemical reaction that require input of energy

Answer 27

endergonic (endothermic)

anabolic reactions

Question 28

chemical reaction that release energy stored in bonds

Answer 28

exergonic (exothermic)

catabolic reactions

Question 29

1st law of thermodynamics

Answer 29

energy is neither created nor destroyed

total energy before and after energy conversion in a reaction is the same

Question 30

2nd law of thermodynamics

Answer 30

disorder tends to increase
(Entropy is increased)
(some energy becomes unavailable for doing work)

Question 31

measure of the disorder in a system

Answer 31

entropy