exam 1 (txtbook) Flashcards
(131 cards)
1
Q
nucleus contains..
A
protons and neutrons
2
Q
electron cloud contains
A
electrons
3
Q
cation is
A
positively charged and has fewer electrons than protons
4
Q
anion is
A
negatively charged and has more electrons than protons
5
Q
mass number is
A
the total number of protons and neutrons in the nucleus
6
Q
isotopes have different…
A
mass numbers
7
Q
atomic weight is
A
the weighted avg of the mass of all its isotopes in AMU
8
Q
shells are numbered…
A
1, 2, 3
9
Q
types of orbitals?
A
s, p, d, f
10
Q
each shell contains a certain number of
A
orbitals
11
Q
an orbital is a region of space that is
A
high in electron density
12
Q
each orbital can have a max of
A
2 electrons
13
Q
what is higher in E: s or p orbital?
A
p orbitals
14
Q
first row of PT has only
A
one orbital in the first shell (1s orbital)
15
Q
second row of PT has a
A
filled first shell of electrons (all 2nd row elements have a 1s2 configuration)
16
Q
second row can accept
A
2s orbital
3 2p orbitals (8 e- max)
17
Q
outer most electrons are
A
valence electrons
18
Q
because each of the four orbitals in the second shell can hold two electrons, there is a
A
max of 8 electrons for elements in the second row
19
Q
group number of second row elements reveals
A
its number of valence electrons
i.e. carbon in group 4A = 4 valence electrons
20
Q
joining two or more compounds =
A
COMPOUNDS
21
Q
through bonding, atoms attain a
A
complete outer shell of valence electrons
22
Q
through bonding: atoms gain/lose/share electrons to
A
attain the electronic configuration of the noble gas closest to them in the PT
23
Q
a first row element like hydrogen can accomodate…
A
two electrons around it
24
Q
a second row element is generally
A
most stable with eight valence electrons around it like neon
25
octet rule
elements with 8 valence electrons around it
26
ionic bonding is
the result of transferring electrons from one element to another
27
covalent bonding is
the result of sharing electrons b/w two nuclei
28
type of bonding is determined by location of...
an element in the PT
29
ionic bond generally occurs when elements on
far left side of the PT combine w far right side elements
30
resulting ions from ionic bonding are held...
together by extremely strong electrostatic interactions
31
a positively charged cation formed from the
element on the left side attracts an anion formed from the right side elements
32
examples of ionic inorganic compounds?
NaCl, KI
33
covalent bonding occurs with elements in the
middle of the PT and between elements on same side of the tablea
34
a covalent bond is a
two electron bond
35
compound with covalent bonds is called
a compound
36
how to calculate the predicted number of bonds
8 - number of valence electrons
37
atoms with 1, 2, 3, or 4 valence electrons form
1, 2, 3, 4 bonds respectively in neutral molecules
38
when second row elements form fewer than four bonds...
their octets consist of both bonding electrons and nonbonding electrons
39
unshared electrons are also called
lone pairs
40
lewis structures are
electron dot representations for molecules
41
three rules for lewis structures
1) draw only valence electrons
2) give every 2nd row element no more than 8 electrons
3) give each hydrogen two electrons
42
formal charge =
of valence electrons - number of electrons an atom 'owns'
43
an atom owns all of its..
unshared electrons and half of its shared electrons
44
number of electrons owned =
number of unshared electrons + 1/2 (number of shared electrons)
45
the sum of the formal charges on the individual atoms =
the net charge on the molecule or ion
46
exceptions to the octet rule?
hydrogen because it accommodates only 2 electrons in bonding
- additionally boron and beryllium, phosophorus, sulfur
47
resonance structures are formed when
there are multiple lewis structures for a molecule
- same placement of atoms but a different arrangement of electrons
48
resonance hybrid
shows characteristics of both resonance structures
49
resonance allows
certain electron pairs to be DELOCALIZED over two or more atoms, adding stability
50
resonance stabilized means
a molecule has two or more resonance structures
51
are resonance structures real?
no (don't accurately represent the structure of a molecule or ion)
52
are resonance structures in equilibrium?
no (no movement of electrons from one form to another)
53
are resonance structures isomers?
no - they differ ONLY in the arrangement of electrons
two isomers are different because of the arrangement of atoms AND electrons
54
how to draw a resonance structure
1) two RS differ in position of multiple bonds and non-bonded electrons
2) placement of atoms and single bonds ALWAYS stays the same
3) two RS must have the same number of unpaired electrons
4) MUST BE VALID LEWIS STRUCTURES. hydrogen must have two electrons and a second-row element can have no more than 8 electrons
55
curved arrow notation is...
a convention that shows how electron position differs between the two resonance forms
56
curved arrow always
begins at an electron pair; ends at an atom or bond
57
what are carbocations?
positively charged carbon atoms that are unstable intermediates because they contain a carbon atom lacking an octet of electrons
58
"exceptions" to resonance structures?
- RS can NEVER have more than 8 electrons (i.e. carbon can't have 10 electrons)
- RS CAN have an atom with fewer than 8 electrons
59
what are heteroatoms?
an atom other than carbon or hydrogen
60
what is a resonance hydrid?
composite of all possible resonance structures (electrons pairs are drawn in diff locations in individual resonance structures are delocalized)
61
is the resonance structure more stable?
YES, because the resonance hybrid is more stable than any resonance structure because it delocalizes electron density over a larger volume
62
when all resonance forms are identical...
each resonance form contributes equally to the hybrid
63
when two resonance structures are different...
the hybrid looks more like the "better" resonance structure
64
the major contributor is the...
"better" resonance structure
65
minor contributors are...
all the other resonance structures
66
the hybrid is the...
weighted average of the contributing resonance structures
67
what makes a resonance structure 'better'?
- more bonds
- fewer charges
68
two common differences amongst resonance structures?
1) position of a multiple bond
2) site of charge
69
notation for double bond position?
use a dashed line for a bond that is single in one resonance structure and double in another
70
notation for location of charge?
partial neg charge and partial pos charge for an atom that is neutral in one RS and charged in the other
71
what is bond length?
average distance between center of two bonded nuclei (reported in pm - picometers)
72
trend for bond length?
decreases across a row of the PT as atom size DECREASES
73
bond length increases...
down a column as atom size INCREASES
74
what does bond angle determine?
the shape around any atom bonded to two other atoms
75
to determine the bond angle and shape around a given atom...
first count how many groups surround the atom
76
a group is either an
atom or a lone pair of electrons
77
use (x) to determine the shape
VSEPR (based on the fact that electron pair repel each other)
78
second row element has only three possible arrangements:
two groups (linear, 180)
three groups (trigonal planar, 120)
four groups (tetrahedral, 109.5)
defined by the number of the grounds surrounding it
79
any atom surrounded by only two groups is...
LINEAR and has a bond angle of 180 degrees
- no lone pair = 180 degree bond angle
80
any atom surrounded by three groups is...
trigonal planar and has bond angles of 120 degrees
- no lone pair = 120 degrees
81
any atom surrounded by four groups is...
tetrahedral and has bond angles of ~109.5 degrees
81
molecular shape of ammonia and water?
trigonal pyramidal (bond angle is 107 degrees)
- one of the groups around N is a nonbonded electron pair
82
types of shorthand representations used for organic compounds
condensed
skeletal
83
condensed structures rules
1) all atoms are drawn in but two-electron bond lines are generally omitted
2) atoms are usually drawn next to the atoms to which they are bonded
3) parentheses are used around similar groups bonded to the same atom
4) lone pairs are omitted
84
to interpret a condensed formula...
best to start at left side of molecules and MAKE SURE THAT carbon atoms are tetravalent
85
skeletal structures rules
1) assume a carbon is located at the junction of any two lines or at the end of any line
2) assume each carbon has enough hydrogens to make it tetravalent
3) drawn in all heteroatoms and hydrogens directly bonded to them
86
lowest energy arrangement of all electrons is...
the ground state
87
a sigma bond is...
a single bond
- concentrates electron density on the axis that joins 2 nuclei
88
hybridization is...
the combo of two or more atomic orbitals to form the same number of hybrid orbitals
- each having the same shape and energy
89
one 2s orbital and three 2p orbitals =
four sp3 hybrid orbitals
90
one 2s orbital and two 2p orbitals =
three sp2 hybrid orbitals
91
one 2s orbital and one 2p orbitals =
two sp hybrid orbitals
92
sp2 and sp hybridization leave...
one and two 2p orbitals unhybridized on each atom
93
forming two sp hybrid orbitals uses
one p and two p orbitals, leaving two 2p orbitals unhybridized
94
forming three sp2 hybrid orbitals uses
one 2s and two 2p orbitals, leaving one 2p orbital unhybridized
95
types of hybrid orbitals
2 groups, 2 orbitals used, two sp hybrid orbitals
3 groups, 3 orbitals, three sp2 hybrid orbitals
4 groups, 4 orbitals, four sp3 hybrid orbitals
96
what orbitals are used to form the two bonds of the C-C double bond?
b/c C has 4 valence electrons, each of these orbitals has one electron that can be used to form a bond
- remember: sp2 hybrid orbitals are formed from one 2s and two 2p orbitals, leaving one 2p orbital unhybridized
97
pi bond is..
weaker than sigma bonds
98
sigma bond is formed by
end on overlap of two sp2 hybrid orbitals
99
pi bond is formed by
side by side overlap of two 2p orbitals
100
carbon-carbon triple bond has three components:
1) a sigma bond formed by end on overlap of two sp hybrid orbitals
2) two pi bonds formed by side by side overlap of two sets of 2p orbitals
101
covalent bonding in carbon compounds
4 groups bonded to C, sp3 hybridization, 109.5 degrees, one sigma bond
3 groups, sp2, 120 deg, one sigma + one pi bonds
2 groups, sp, 180 deg, one sigma + two pi bonds
102
as number of electrons between two nuclei increases...
bonds become shorter and stronger
103
triple bonds are shorter ad stronger than double bonds which are
shorter and stronger than single bonds
104
double bonds consisting of...
both a sigma and pi bonds are stronger
105
the pi component of the double is
weaker than the sigma component
106
higher hybridization means
decreasing bond strength
107
increasing bond length means
weaker bonds
108
percent s character indicates
the fraction of a hybrid orbital due to the 2s orbital used to form it
109
sp hybrid has how much s character
one 2s orbital / two hybrid orbitals = 50% s character
110
sp2 hybrid
one 2s / three hybrid = 33% s character
111
sp3 hybrid
one 2s orbital / 4 hybrid orbitals = 25% s character
112
as s-character increases...
a hybrid orbital holds its electron closer to the nucleus and the bond becomes shorter/stronger
113
electronegativity is the measure of
an atom's attraction for electrons in a bond (increases as a row of PT, decreases down a column)
114
carbon carbon bond is
nonpolar
115
c-h bonds are
nonpolar b/c electronegativity diff is small
116
c-o bond is
polar/polar covalent
- has a dipole (partial separation of charge)
117
usually a polar bond will be one in which the
electronegativity difference between two atom is > 0.5 unit
118
electrostatic potential map shows
the distribution of electron density in a molecule
119
because alkanes have no functional group, they are...
much less reactive than other organic compounds
120
alkanes are aliphatic hydrocarbon having only...
C--C and C--H sigma bonds
121
because their carbon atoms can be joined together in chains or rings...
alkanes can be categorized as acyclic or cyclic
122
acyclic alkanes have the molecular formula...
CnH2n+2 where n = an integer
123
acyclic alkanes contain only
linear and branched chains of carbon atoms
124
acyclic alkanes are also called
saturated hydrocarbons b/c they have the max number of hydrogen atoms per carbon
125
cycloalkanes contains carbons...
joined in one or more rings
126
general formula of cycloalkanes?
CnH2n
127
cycloalkanes have fewer
H atoms than an acyclic alkane with the same number of carbons
128
what are isomers?
two different compounds with the same molecular formula (constitutional or stereoisomers)
129
drugs have three names:
systemic: follows nomenclature rules and indicates IUPAC name
generic: official name
trade: name assigned by manufacturing company
130
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