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General Biology > Chapter 2: "The Chemical Bases Of Life" > Flashcards

Chapter 2: "The Chemical Bases Of Life" Flashcards

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0
Q

Inorganic compounds:

A

Small, simple substances.

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1
Q

The chemistry and physics of the molecules that constitute living things is called:

A

Molecular biology.

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2
Q

Organic compounds:

A

carbon-containing compounds that are generally large and complex.

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3
Q

Electron:

A

Is a particle that carries a unit of negative electric charge.

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4
Q

Proton:

A

Carries a unit of positive charge.

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5
Q

Neutron:

A

Is an uncharged particle. In an electrically neutral atom, the number of electrons is equal to the number of protons.

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6
Q

Clustered together, protons and neutrons compose the:

A

Atomic nucleus.

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7
Q

Every element has a fi xed number of protons in the atomic nucleus, known as the_________.

A

Atomic number.

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8
Q

Oxygen:

A

Required for cellular respiration; present in most organic compounds; component of water.

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9
Q

Carbon:

A

Forms backbone of organic molecules; each car-bon atom can form four bonds with other atoms.

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10
Q

Hydrogen:

A

Present in most organic compounds; component of water; hydrogen ion (H+) is involved in some energy transfers

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11
Q

Nitrogen:

A

Component of proteins and nucleic acids; component of chlorophyll in plants.

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12
Q

Calcium:

A

Structural component of bones and teeth; cal-cium ion (Ca2+) is important in muscle contrac-tion, conduction of nerve impulses, and blood clotting; associated with plant cell wall.

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13
Q

Phosphorus:

A

Component of nucleic acids and of phospholipids in membranes; important in energy transfer reac-tions; structural component of bone.

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14
Q

Potassium:

A

Potassium ion (K+) is a principal positive ion (cat-ion) in interstitial (tissue) fl uid of animals; impor-tant in nerve function; aff ects muscle contraction; controls opening of stomata in plants.

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15
Q

Sulfur:

A

Component of most proteins.

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16
Q

Sodium:

A

Sodium ion (Na+) is a principal positive ion (cat-ion) in interstitial (tissue) fl uid of animals; impor-tant in fl uid balance; essential for conduction of nerve impulses; important in photosynthesis in plants.

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17
Q

Magnesium:

A

Needed in blood and other tissues of animals; ac-tivates many enzymes; component of chlorophyll in plants.

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18
Q

Chlorine:

A

Chloride ion (Cl−) is principal negative ion (anion) in interstitial (tissue) fl uid of animals; important in water balance; essential for photosynthesis.

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19
Q

Iron:

A

Component of hemoglobin in animals; activates certain enzymes.

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20
Q

The periodic table:

A

Is a chart of the elements arranged in order by atomic number.

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21
Q

atomic mass unit (amu):

A

One (amu) is equal to the approximate mass of a single proton or a single neutron. Protons and neutrons make up almost all the mass of an atom. Th e mass of a single electron is only about 1/1800 the mass of a proton or neutron.

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22
Q

Most elements consist of a mixture of atoms with different numbers of neutrons and thus different masses. Such atoms are called:

A

Isotopes.

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23
Q

Isotopes of the same element have the same number of ____and____; only the number of ______ varies.

A

protons and electrons. neutrons.

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24
Q

some isotopes are unstable and tend to break down, or decay, to a more stable isotope (usually becoming a diff erent element); such_______ emit radiation when they decay.

A

Radioisotopes.

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25
Q

Radioactive decay can be detected by a method known as:

A

Autoradiography.

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26
Q

Electrons move through characteristic regions of 3-D space, called_____. Each_____ contains a maximum of ___ electrons.

A

orbitals.orbital, 2.

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27
Q

it is impossible to know an electron’s position at any given time, orbitals are most accurately depicted as:

A

Electron clouds.

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28
Q

Th e energy of an electron depends on the orbital it occupies. Electrons in orbitals with similar energies, said to be at the same principal energy level make up an:

A

Electron Shell.

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29
Q

Th e most energetic electrons, known as valence electrons, are said to occupy the:

A

Valence shell.

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30
Q

The________ is represented as the outermost concentric ring in a Bohr model.

A

Valence Shell.

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31
Q

An ____ can move to an orbital farther from the nucleus by receiving more energy, or it can give up energy and sink to a lower energy level in an orbital nearer the nucleus.

A

Electron.

32
Q

The chemical behavior of an atom is determined primarily by the number and arrangement of its:

A

Valence electrons.

33
Q

T he valence shell of hydrogen or helium is full (stable) when it contains 2 electrons. The valence shell of any other atom is full when it contains:

A

8 electrons.

34
Q

Elements in the same vertical column (belonging to the same group) of the periodic table have similar chemical properties because:

A

Their valence shells have similar tendencies to lose, gain, or share electrons.

35
Q

A chemical compound:

A

Consists of atoms of two or more different elements combined in a fixed ratio.

36
Q

Two or more atoms may become joined very strongly to form a stable particle called a:

A

Molecule.

37
Q

A _____ is a shorthand expression that describes the chemical composition of a substance.

A

Chemical formula.

38
Q

In the simplest formula (also known as an empirical formula):

A

The subscripts give the smallest whole-number ratios for the atoms present in a compound.

39
Q

An example of the simplest formula for hydrazine is:

A

NH2, indicating a 1:2 ratio of nitrogen to hydrogen.

40
Q

A molecular formula is:

A

The subscripts indicate the actual numbers of each type of atom per molecule. Th e molecular for-mula for hydrazine is N2H4, which indicates that each molecule of hydrazine consists of two atoms of nitrogen and four atoms of hydrogen.

41
Q

The structural formula:

A

Shows not only the types and numbers of atoms in a molecule but also their arrangement.

42
Q

An example of the structural formula for water is .

A

H-O-H

43
Q

The molecular mass of a compound is the sum of the atomic masses of the component atoms of a single molecule; thus, the molecular mass of water, H2O, is:

A

(hydrogen: 2 × 1 amu) + (oxygen: 1 × 16 amu), or 18 amu.

44
Q

The amount of an element or compound whose mass in grams is equivalent to its atomic or molecular mass is:

A

1 mole (mol).

45
Q

1 mol of any substance always has exactly the same number of units, whether those units are:

A

Small atoms or large molecules.

46
Q

The very large number of units in a mole, 6.02 × 10^23, is known as:

A

Avogadro’s number.

47
Q

Atoms can be held together by forces of att raction called:

A

Chemical bonds.

48
Q

Bond energy:

A

Is the energy necessary to break a chemical bond.

49
Q

Covalent bonds:

A

Involve the sharing of electrons between atoms in a way that results in each atom having a fi lled valence shell.

50
Q

Atoms can also be linked by covalent bonds to form molecules; the resulting compound is a:

A

Covalent compound.

51
Q

When one pair of electrons is shared between two atoms, the covalent bond is called a:

A

Single covalent bond.

52
Q

When two pairs of electrons are shared in this way, the covalent bond is called a:

A

Double covalent bond.

53
Q

A triple covalent bond is formed when:

A

Three pairs of electrons are shared between two atoms.

54
Q

When an atom forms covalent bonds with other atoms, the orbitals in the valence shell may become rearranged in a process known as:

A

Orbital hybridization.

55
Q

Electronegativity:

A

Is a measure of an atom’s att raction for shared electrons in chemical bonds.

56
Q

When covalently bonded atoms have similar electronegativities, the electrons are shared equally and the co-valent bond is described as:

A

Nonpolar.

57
Q

A covalent bond between atoms that differ in electronegativity is called a:

A

Polar covalent bond.

58
Q

A polar molecule:

A

Has one end with a partial positive charge and another end with a partial negative charge.

59
Q

positively charged ions are termed:

A

Cations.

60
Q

valence electrons tend to gain electrons from other atoms and become negatively charged:

A

Anions.

61
Q

Cations and anions are involved in energy transformations within the cell such as:

A

The transmission of nerve impulses, muscle contraction, and many other biological processes.

62
Q

An_______ forms as a consequence of the att-raction between the positive charge of a cation and the negative charge of an anion

A

Ionic bond.

63
Q

Ionic compound:

A

Is a substance consisting of anions and cations bonded by their opposite charges.

64
Q

As a liquid it is capable of dissolving many substances, particularly those that are polar or ionic, because of the polarity of water molecules. The localized partial positive charge (on the hy-drogen atoms) and partial negative charge (on the oxygen atom) on each water molecule attract and surround the anions and cations, respectively, on the surface of an ionic solid.

A

H2O ( Water)

65
Q

Hydration:

A

In solution, each cation and anion of the ionic compound is surrounded by oppositely charged ends of the water molecules.

66
Q

Van der Waals interactions:

A

A region with a temporary excess of electrons will have a weak negative charge, whereas one with an electron defi cit will have a weak positive charge. Adjacent molecules may interact in regions of slight opposite charge.

67
Q

oxidation–reduction, or:

A

Redox reaction.

68
Q

Oxidation:

A

Is a chemical process in which an atom, ion, or molecule loses one or more electrons.

69
Q

Reduction:

A

is a chemical process in which an atom, ion, or molecule gains one or more electrons.

70
Q

Cohesion:

A

Water molecules have a strong tendency to stick to one another.This is due to the hydrogen bonds among the molecules.

71
Q

Capillary action:

A

which is the tendency of water to move in narrow tubes, even against the force of gravity.

72
Q

Substances that interact readily with water are_______. Examples include table sugar (sucrose, a polar compound) and table salt

A

Hydrophilic (“water-loving”).

73
Q

Many_______substances found in living things are especially important because of their ability to form associations or structures that are not disrupted.

A

Hydrophobic (“water-fearing”).

74
Q

The degree of a solution’s acidity is generally expressed in terms of______, defined as the negative logarithm (base 10) of the hydrogen ion concentration (expressed in moles per liter):

A

pH.

75
Q

Acid:

A

Is a substance that dissociates in solution to yield hydrogen ions (H+) and anions.

76
Q

Base:

A

Is defined as a proton acceptor. Most bases are sub-stances that dissociate to yield a hydroxide ion (OH−) and a cation when dissolved in water.

77
Q

Buffer:

A

Is a substance or combination of substances that resists changes in pH when an acid or base is added.

General Biology (9 decks)

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