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Biology 3 > Chapter 2 > Flashcards

Chapter 2 Flashcards

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1
Q

atomic number

A

the atomic number corresponds to the number of protons

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2
Q

atomic weight

A

corresponds to the number of the protons plus neutrons

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3
Q

why does the atomic weight appear in decimal form?

A

the decimal results from the fact that the atomic weight is an average of all naturally occurring forms of the element, which vary in the number of neutrons

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4
Q

how many naturally occurring elements are there on earth?

A

92

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5
Q

How many elements are found inside living organisms?

A

25

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6
Q

How many trace elements are there?

A

14

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7
Q

trace elements

A

required in only tiny amounts within organisms, living cells cannot survive without them.

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8
Q

What four elements make up the bulk of living organisms?

A

Oxygen (65%), carbon (18.5%), hydrogen (9.5%), and nitrogen (3.3%)

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9
Q

Is a dietary supplement that contains gold beneficial to your body?

A

No. It is not an element required by living cells.

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10
Q

What are some weird elements that living things like us need to survive?

A

cobalt, copper, iron, silicon, tin, zinc, chromium

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11
Q

what are the two types of chemical bonds?

A

ionic and covalent

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12
Q

what are ionic bonds?

A

a bond formed through the transfer of one or more electrons from one atom to another. Both atoms in the exchange become ions through the donating/receiving of electrons.

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13
Q

what are chemical bonds?

A

the result of attraction between atoms

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14
Q

isotopes

A

elements that vary in the number of neutrons and are named according to atomic weight (weight of protons + neutrons), for example, nitrogen-13.

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15
Q

ions

A

elements that vary in the number of electrons in the electron cloud. ions carry a charge. Named for the amount of extra electrons. (Ex. N^3-)

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16
Q

true or false. atoms are neutrally charged.

A

True

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17
Q

ions carry only a negative charge (T or F).

A

False, charges can be either positive or negative, and ions can be positive if they have lost electrons.

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18
Q

What holds together atoms in an ionic bond?

A

unequal charges created by the transfer of electrons.

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19
Q

What compound is an example of an ionic bond?

A

NaCl

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20
Q

what are covalent bonds?

A

bonds formed from the sharing of one or more electrons. Each bond consists of a pair of shared electrons.

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21
Q

what is an example of a covalent bond?

A

H2O

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22
Q

how are single bonds and double bonds in covalent bonds represented?

A

single bond: O–O

double bond: O=O

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23
Q

what are the two types of covalent bonds?

A

nonpolar and polar

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24
Q

nonpolar bond

A

electrons are shared equally between the two atoms in the bond

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25
Q

what compound has a covalent nonpolar bond

A

methane gas (CH4)

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26
Q

what compound has a polar covalent bond?

A

water

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27
Q

polar bond

A

A bond formed from sharing of electrons where the electrons are more strongly attracted to one atom than the other, resulting in the bond having two oppositely charged poles.

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28
Q

polar and charged mean the same thing. (T or F)

A

False, something can be polar and be neutrally charged.

29
Q

what causes the polarity in a polar bond?

A

Because the electrons are no longer evenly spaced between the two atoms, there is a slightly negative pole (end) and a slightly positive pole.

30
Q

True or false, a polar covalent bond overall carries no charge.

A

True

31
Q

In water, to which element are the electrons more attracted?

A

The electrons are drawn more to the oxygen nucleus than the hydrogen nucleus.

32
Q

what is a hydrogen bond?

A

the bond formed by the facing of negatively charged oxygen ends of water molecules towards the positively charged hydrogen ends of other water molecules.

33
Q

what forms liquid water as we know it?

A

the ability of a single water molecule to participate in several hydrogen bonds.

34
Q

what kind of bond holds the atoms together within a water molecule?

A

polar covalent bond

35
Q

what kind of bond acts as the binding force between water molecules?

A

hydrogen bonds

36
Q

are bonds between water molecules are strong or weak?

A

weak

37
Q

Most liquids do not expand when they freeze (true or false)

A

true

38
Q

What allows ice to float on the surface of water?

A

water expands and the molecules are held farther apart when it freezes

39
Q

what biological function does the flotation of ice serve?

A

during winter, a thing layer of floating ice insulates the water below the surface, allowing life to survive until the spring thaw.

40
Q

what is the molecular structure difference between ice and liquid water?

A

liquid water molecules jostle, constantly break and reform, while frozen water molecules are held rigidly in place

41
Q

the structure of liquid water molecules make water an effective what?

A

solvent

42
Q

what makes water important for earth’s temperature regulation?

A

liquid water readily absorbs and releases heat and therefore resists temperature change more than most substances

43
Q

cohesion

A

the ability of water molecules to stick together due to hydrogen bonding

44
Q

what is surface tension?

A

a film-like surface on which items (like pond skaters) can be suspended (caused by hydrogen bonds)

45
Q

adhesion

A

the clinging of one substance to another , causes water droplets to stick to surfaces

46
Q

in which substance do most life-maintaining chemical reactions occur?

A

water

47
Q

aqueous solution

A

a solution that contains a substance dissolved in water

48
Q

what determines the pH of a solution?

A

the concentration of hydrogen ions (H+)

49
Q

the pH scale runs from __ to __.

A

0 to 14.

50
Q

Greater H+ concentrations are indicated by a (lower/higher) pH number.

A

Lower

51
Q

Lower pH indicates a more basic solution (T or F)

A

False

52
Q

what is an acid?

A

a chemical that, when dissolved in water, releases H+ ions. an acid has a pH between 0 and 7.

53
Q

at what pH level do hydrogen ions equal hydroxide (OH-) ions?

A

7

54
Q

what are buffers?

A

chemicals that minimize changes in pH by accepting H+ ions when they are present in excess and donating H+ ions when they are short in supply.

55
Q

example of how buffers work in the human body

A

there are chemicals present in blood that counteract a drop in pH (more acidic) that occurs every time you exercise.

56
Q

what is a base?

A

A base is a chemical that, when dissolved in water, removes H+ ions from the solution by combining them with OH-. A base has a pH anywhere from 7 to 14.

57
Q

describe ocean acidification.

A

ocean acidification is the lowering of pH in the world’s oceans due to the dissolving of excess carbon dioxide. The lowered pH inhibits chemical reactions needed to build skeletons/shells in coral reef ecosystems.

58
Q

organic compounds

A

molecules that contain carbon bonded to some other element

59
Q

why is life considered to be carbon-based?

A

carbon can bond with up to four other atoms, forming the capacity for large, highly diverse, branched chains that can serve as the basic skeletons for a wide variety of chemical compounds

60
Q

every organic compound contains a skeleton of ______ atoms.

A

carbon

61
Q

How much carbon dioxide from the atmosphere is absorbed by the oceans on a daily basis?

A

20 million metric tons

62
Q

What is the chemical reaction responsible for the oceans becoming more acidic?

A

carbon dioxide reacts with seawater, forming carbonic acid

63
Q

what edible sea creatures are most at risk due to ocean acidification?

A

shellfish

64
Q

what are functional groups?

A

sets of atoms attached to carbon skeletons.

65
Q

what is the function of functional groups?

A

they participate in chemical reactions and as a result determine the overall properties of an organic compound.

66
Q

examples of functional groups:

A

ethyl alcohol, amino acids, adenosine triphosphate

67
Q

what are the four classes of large organic molecules important to life on Earth?

A

carbohydrates, lipids, proteins, and nucleic acids.

68
Q

examples of carbohydrates

A

cellulose and glucose

Biology 3 (11 decks)

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