Organic 1: Structure Determines Properties Flashcards Preview

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Flashcards in Organic 1: Structure Determines Properties Deck (85)
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1
Q

Atomic number Z

A

each element is characterized by this, which is equal to the number of protons in its nucleus

2
Q

Wave functions

A

mathematical descriptions of the electron wave, symbolized by Greek letter psi; AKA orbitals

3
Q

Psi^2

A

probability of finding an electron at a particular spot relative to an atom’s nucleus = psi^2 at that point

4
Q

Principal quantum number n

A

letter s is preceded by this, which specifies the shell and is related to the energy of the orbital

5
Q

Shell

A

group of orbitals that have the same principal quantum number n

6
Q

Boundary surfaces

A

more common to represent orbitals by these; encloses the region where the probability of finding an electron is high (90-95%)

7
Q

Spin

A

synonymous with spin quantum number

8
Q

Spin quantum number

A

can have a value of +1/2 or -1/2

9
Q

Pauli Exclusion Principle

A

two electrons may occupy the same orbital only when they have opposite (paired) spins; for this reason, no orbital can contain more than 2 electrons

10
Q

Period

A

row of the periodic table; corresponds to the principal quantum number of the highest numbered occupied orbital

11
Q

Nodal surfaces

A

regions of a single orbital may be separated by these where the wave function changes sign and the probability of finding an electron is zero

12
Q

Hund’s Rule

A

general principal for orbitals of equal energy; when 2 orbitals are of equal energy, they are populated by electrons so that each one is half-filled before either one is doubly occupied

13
Q

Valence electrons

A

outermost electrons, the ones most likely to be involved in chemical bonding and reactions

14
Q

Valence shell

A

the group of orbitals, filled and unfilled, responsible for the characteristic chemical properties of an atom

15
Q

Main-group elements

A

for these, the number of valence electrons is equal to its group number in the periodic table

16
Q

Octet

A

having 8 electrons in the valence shell

17
Q

Noble (rare) gases

A

helium, neon, and argon are in this class; characterized by extremely stable, “closed-shell” electron configuration; very unreactive

18
Q

Compounds

A

atoms combine with one another to give these, having properties different from the atoms they contain

19
Q

Chemical bond

A

attractive force between atoms in a compound

20
Q

Ionic bond

A

force of attraction between oppositely charged species (ions)

21
Q

Cations

A

positively charged ions

22
Q

Anions

A

negatively charged ions

23
Q

Isoelectronic

A

species that have the same number of electrons

24
Q

Ionization energy

A

large amount of energy that must be transferred to any atom to dislodge an electron

25
Q

Endothermic

A

processes that absorb energy

26
Q

Exothermic

A

energy-releasing reactions; energy change for this process has a negative sign

27
Q

Electron affinity

A

energy change for addition of an electron to an atom

28
Q

Electrostatic

A

attractive forces between oppositely charged particles; AKA coulombic attractions; what is meant by an ionic bond between 2 atoms

29
Q

Covalent (shared electron pair) model

A

first suggested by GN Lewis (1916); proposed that a sharing of 2 electrons by 2 hydrogen atoms permits each one to have a stable, close-shell electron configuration analogous to helium

30
Q

Lewis structures

A

structural formulas in which electrons are represented as dots; customary to represent a shared electron-pair bond by a dash

31
Q

Bond dissociation enthalpy

A

amount of energy required to dissociate a hydrogen molecule H2 to two separate hydrogen atoms

32
Q

Unshared pairs

A

Valence electrons not involved in bonding

33
Q

Octet rule

A

in forming compounds, elements gain, lose, or share electrons to achieve a stable electron configuration characterized by 8 valence electrons

34
Q

Double bond

A

bond formed by the sharing of 4 electrons between 2 atoms

35
Q

Triple bond

A

bond formed by the sharing of 6 electrons between 2 atoms

36
Q

Polar covalent

A

if one atom has a greater tendency to attract electrons toward itself than the other, the electron distribution if polarized and the bond is described at this

37
Q

Electronegativity

A

tendency of an atom to attract the electrons in a covalent bond toward itself

38
Q

Electrostatic potential map

A

uses the colors of the rainbow to show charge distribution

39
Q

Bond dipole moments

A

exists whenever opposite charges are separated from each other; direction of this is toward the more electronegative atom

40
Q

Dipole moment mu

A

product of the amount of the charge e multiplied by the distance d between the centers of charge (mu = e x d)

41
Q

debye (D)

A

unit customarily used for measuring dipole moments; 1D = 1 x 10^-18 esu cm

42
Q

Formal charges

A

the charge, either positive or negative, of an atom calculated by subtracting the number of valence electrons in the neutral atom a number equal to the sum of its unshared electrons plus half the electrons in its covalent bonds

43
Q

Molecular formula

A

tells us which atoms and how many of each are present in a compound

44
Q

Connectivity

A

order in which atoms are connected

45
Q

Isomers

A

different compounds that have the same molecular formula

46
Q

Constitutional isomers

A

isomers that differ in connectivity; AKA structural isomers

47
Q

Stereoisomers

A

isomers that differ in arrangement of atoms in space

48
Q

Resonance

A

when 2 or more Lewis structures that differ only in the distribution of electrons can be written for a molecule, no single Lewis structure is sufficient to describe its true electron distribution

49
Q

Resonance hybrid

A

the collection of Lewis structures that, taken together, represent the electron distribution in a molecule

50
Q

Contributing structures

A

the various resonance structures that can be written for a molecule

51
Q

Localized

A

Lewis formulas show electrons as this; they either are shared between 2 atoms in a covalent bond or are unshared electrons belonging to a single atom

52
Q

Delocalized

A

electrons shared by several nuclei

53
Q

Curved arrows

A

writing the various Lewis formulas that contribute to a resonance hybrid can be made easier by using these to keep track of delocalized electrons; converts 1 Lewis structure to another by moving electron pairs using these

54
Q

Condensed formulas

A

leave out some, many, or all of the covalent bonds and use subscripts to indicate the number of identical groups attached to a particular atom

55
Q

Bond-line formula

A

AKA carbon skeletal diagram; we assume that there is a carbon atom at every vertex and at the end of a line

56
Q

Heteroatoms

A

atoms that are neither carbon nor hydrogen

57
Q

Solid wedge

A

represents a bond that projects toward you

58
Q

Dashed wedge

A

represents a bond that points away from you

59
Q

Simple line

A

represents a bond that lies in the plane of the paper

60
Q

Valence shell electron-pair repulsion (VSEPR) model

A

rests on the idea that an electron pair, either a bonded pair or an unshared pair, associated with a particular atom will be as far away from the atom’s other electron pairs as possible

61
Q

Tetrahedral angle

A

permits four bonds to be maximally separated; characterized by angles of 109.5 degrees; ex. water, ammonia, methane

62
Q

Molecular dipole moment

A

resultant of all of the individual bond dipole moments of a substance

63
Q

Double-barbed arrow

A

shows the movement of a PAIR of electrons, either a bonded pair or a lone pair

64
Q

Single-barbed (fishhook) arrow

A

shows the movement of 1 electron

65
Q

Acid

A

substance that ionizes to give protons when dissolved in water

66
Q

Base

A

ionizes to give hydroxide ions

67
Q

Acidity constant

A

equilibrium constant Ka; measures the strength of a weak acid

68
Q

pKa

A

-log (base 10) Ka

69
Q

Bronsted-Lowry acid

A

proton donor

70
Q

Bronsted-Lowry base

A

proton acceptor

71
Q

Conjugate acid

A

base and this differ by a single proton

72
Q

Conjugate base

A

acid and this differ by a single proton

73
Q

Oxonium ion

A

systematic name for the conjugate acid of water (H3O+)

74
Q

Hydronium ion

A

common name for H3O+

75
Q

Basicity constant Kb

A

Bronsted-Lowry approach involving conjugate relationships between acids and bases make this unnecessary

76
Q

Inductive effects

A

structural effects that are transmitted through bonds

77
Q

Strong acid

A

one that is stronger than H3O+

78
Q

Weak acid

A

one that is weaker than H3O+

79
Q

Strong base

A

one that is stronger than OH-

80
Q

Lewis acid

A

electron-pair acceptor

81
Q

Lewis base

A

electron-pair donor

82
Q

Lewis acid/Lewis base complex

A

species that results by covalent bond formation between a Lewis acid and a Lewis base

83
Q

Substitution

A

one atom or group replaces another in a reaction

84
Q

Nucleophiles

A

nucleus seekers; Lewis bases that use an unshared pair to form a bond to some other atom

85
Q

Electrophiles

A

electron seekers; Lewis acids

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