ORGO Chp 2

a double bond is made up of

1 sigma & 1 pi bond

3 types of molecular orbitals

1. antibonding (higher in energy; nodes btw bonding nuclei) 2. nonbonding (not involved in bonding) 3. bonding (lower in energy; signif density btw bonding nuclei)

H-N-H bond angle in ammonia is ____, whereas the H-O-H bond angle inw ater is ____. the bond angles are _____ than H-C-H bond angle in methane bc of the unshared pair of e-.

107; 105; smaller

the structure of n-hexane contains _____ methyl groups & ____ methylene groups.

2, 4

sp2 hybrid orbitals

3 orbitals generated by mixing the carbon 2s orbital w/ 2 of the 2p orbitals - one 2p orbital is UNhybridized - all 3 are of equal energy

the hybridization of 1 s & 2 p orbitals will result in the formation of ______ sp2 hybrid orbitals. this will leave ____ unhybridized p orbital(s), which is/are at right angles to the hybrid orbitals.

3, 1

the orbital hybridization model accounts for C having ____ bonds rather than ___, the bonds are ____ than they would be int he absence of hybridization & are arranged in a ______ fashion around C.

4; 2; stronger; tetrahedral

by mixing the 2s, 2px, 2py, & 2pz orbitals you form ____ new orbitals called ________

4; sp3 hybrid orbitals - b/c they come form 1 s orbital & 3 p orbitals

H3C-C--O H the structure contains __ sigma bonds & ___ pi bonds. the C--O double bond is formed by the overlap of 2 ___-hybridized orbitals to form the sigma bond & 2 ___ orbitals to form the pi bond.

6 (include C-H bonds); 1; sp2; p

reduction results in a decrease in the # of _____ bonds

C-Z **Z represents any element with a greater electroneg than H

general molecular formula of alkanes

Cn H2n+2

T/F: heat of combustion can be used to determine the relative stability of 2 isomer alkanes, since the more stable isomer will have a higher heat of combustion.

False! ** the more stable isomer will have a LOWER heat of combustion since it's already at a lower energy

what is the correct IUPAC name for the compound CH3CHClCh2ChBrCH3 a) 2-bromo-4-chloropentane b) 2-chloro-4-bromopentane

a ** the 1st locant is on C2 in either direction; however, bromo is placed before cloro alphabetically

select all that correctly describe a sigma bond: a) formed by the overlap of orbitals along the internuclear axis b) has its highest e- density btwn nuclei of the bonding atoms c) formed by overlap of orbitals perpendicular to the internuclear axis d) e- distribution in a sigma bond is spherically symmetrical

a, b

which correctly describe a pi bond? a) multiple bond always contains at least 1 pi bond b) formed by sideways overlap of 2 p orbitals c) is stronger than a sigma bond d) concentrates e- density along the axis between 2 nuclei

a, b

which correctly describe the changes that occur when a covalent compound boils? a) the stronger intermolecular forces, the greater the amount of energy required for the change from liquid to gas b) compound becomes less ordered & intermolec forces are broken c) energy is released as the attractive forces btwn molecs are broken d) compound w/ weaker intermolecular forces will release more energy & will have a higher BP

a, b ** energy is required/absorved in order to break attractive forces, NOT released

select all that correctly describe a covalent bond a) if 2 atoms in a covalent bond approach too closely, the system will become less stable b) as 2 atoms form a covalent bond, the energy of the system decreases in a stable covalent bond, nucleus-e- attractions dominate the system d) results from the attraction btwn the e- of 2 different atoms

a, b, c

select all that correctly describe the bonding in an alkane such as ethane (C2H6) a) the central C-C bond is a sigma bond formed by sp3-sp3 overlap b) the sp3 orbitals of each C atom have a planar geometry c) both C atoms are sp3 hybridized d) each C-H bond is formed by the overlap of 2 sp3 hybrid orbitals

a, c **C-H bonds are formed by the overlap of a C sp3 orbital & a H 1s orbital

select all that correctly describe the different classes of hydrocarbons: a) benzene is an aromatic hydrocarbon b) alkanes are aromatic hydrocarbons c) alkenes are alphatic hydrocarbons d) aromatic hydrocarbons are also called arenes e) alkynes contain 1 pi bond

a, c, d

which correctly describe the bonding e- in methane according to the molecular orbital theory a) bonding e- are more delocalized compared to valence bond description b) all 4 bonding molec orbitals have the same energy c) the lowst-energy bonding MO has no nodes d) 3 of the bonding MOs have the same energy & have 1 node

a, c, d **1 bonding MO is lower in energy than the other 3

select all that correctly describe the complete combustion of alkanes a) it's an exothermic reaction b) alkane undergoes reduction during combustion c) it produces H2 as well as CO2 d) CO2 is 1 of the products formed by complete combustion of an alkane

a, d

which correctly describe van der Waals forces: a) they're very weak attraction between temporary dipoles b) they're the primary intermolec force exhibited by polar molec c) are stronger for smaller molecular d) all covalent compounds exhibit van der waals forces

a, d

select all that correctly describe the bonding in allene, H2C=C=CH2 a) pi bonds are perpendic to each other b) pi bonds are parallel to each other c) the central C is sp2 hybridized d) end C atoms are sp2 hybridized e) central C is sp hybridized

a, d, e

select all that correctly describe the bonding of 2 atoms according to the molecular orbital model of bonding: a) e- fill molecular orbitals in the same way that they fill atomic orbitals b) each pair of atomic orbitals forms 1 molecular orbital c) sigma bonding orbital is designated sigma+ d) for each bonding molecular orbital there's an antibonding molecular orbital e) all atomic orbitals of the bonding atoms combine to form molecular orbitals

a, d, e

Branched-chain alkanes

alkanes that contain only C and H (with only C-C single bonds) but are not linear.

Aliphatic hydrocarbons include 3 major groups

alkanes, alkenes, alkynes

Paraffin hydrocarbons is an older name for ______ & testifies to the low level of _____ of these hydrocarbons

alkanes; reactivity

a substituent such as a methyl in an organic compound is called a(n) _____ group

alkyl

any carbon substituent formed by removing 1 H from an alkane is called a(n) _____ group

alkyl

the functional groups in Ch3Ch2Cl & Ch3Ch2OH are ____ & _____ respectively

alkyl halide; alcohol

Arenes

another name for aromatic hydrocarbons

according to the molecular orbital model of covalent bonding 2 orbitals may combine destructively to produce a ____ molecular orbital which is ____ in energy than the orig atomic orbitals

antibonding; higher

IUPAC system defines a functional group as an ___ or a ____ of atoms that exhibits similar ____ properties whenever it occurs in diff compounds

atom; group; chemical

molecular orbital theory of chemical bonding rests on the notion that, as e- in atoms occupy __________, e- in molecules occupy _______.

atomic orbitals; molecular orbitals

n-alkanes can form a homologous series. this means that ____. a) each successive alkane differs from the previous 1 by a single branch b) each successive alkane differs from the previous by a -CH2- group c) they all have branched chains d) they're all structural isomers of each other

b

the base name is given by the longest continuous chain that begins ______________ a) farthest from the point of attachment b) at the point of attachment

b

what is the orbital hybridization of a carbon atom that's bonded to 4 other atoms? a) sp b) sp3 c) sp2

b

which has the highest heat of combustion? a) 2-methylpentane b) heptane c) 2-methylhexane d) hexane

b **having more C increases the heat of combustion

select all that correctly describe the formation of sp3 hybrid orbitals a) set of 4 sp3 orbitals is arranged in a trigonal planar fashion around the nucleus b) 4 sp3 orbitals of a particular set are equal to each other in energy c) 1 s & 3 p orbitals mix to produce 4 sp3 hybrid orbitals d) the sp3 hybrid orbitals are lower in energy than the original s & p orbitals

b, c - sp3 hybrid orbitals are lower in energy than the p orbitals & higher than the s orbitals

select all that correctly describe a single covalent bond according to the valence bond model: a) e- density is lowest btwn the 2 bonded nuclei b) single bonding orbital is shared btwn the 2 atoms c) overlap of 2 atomic orbitals form 2 bonding orbitals d) 2 atoms bond by the overlap of half-filled orbital from each atom e) bonding e- are most likely to be found btwn the 2 nuclei

b, d, e

the most important aromatic hydrocarbon is

benzene

sigma bond

bond in which the orbitals overlap along a line connecting the atoms - cylindrical symmetry

according to the molecular orbital model of covalent bonding 2 orbitals may combine constructively to produce a ____ molecular orbital which is ____ in energy than the orig atomic orbitals

bonding; lower

select all that correctly describe the relationship btwn alkane structure & boiling point a) cyclic alkane has a lower BP than acyclic alkane w/ the same # of C atoms b) alkane w/ higher molecular weight has a lower BP c) larger SA of an alkane molec increases the BP of a compound d) branched alkane has a lower BP than an unbranched alkane w/ same molecular weight

c, d **cyclopentane has a higher BP than pentane indicative of relatively stronger van de waals forces

which correctly describe the physical properties of alkanes: a) the BP of alkane isomers increases w/ branching in the chain b) alkanes w/ fewer than 4 C tend to be soluble in water c) alkanes are nonpolar compounds d) alkanes ahve lower BP than polar compounds of comparable size e) the MP of alkanes generally increases as the # of C atoms int eh chain increases

c, d, e

steps for naming an acyclic alkane in the correct order a) # the C atoms in the parent chain to give the lowest # to the substituent at the 1st branch pt b) list the substituents in the correct order, as a prefix to the parent name c) find the longest continuous C chain to name the parent d) add the parent name & suffix e) identify the names of the substituents

c, e, a, b, d

molecular orbital model describes bonding as the

combination of all atomic orbitals of all the atoms in a molecule

the heat released when a substance is burned is called the heat of _____ for that substance.

combustion

Alkenes

contain at LEAST 1 carbon-carbon DOUBLE bond

Alkynes

contain at LEAST 1 carbon-carbon TRIPLE bond

the bond formed btwn 2 nonmetal atoms is called a(n) ____ bond. this bond is a result of the attraction btwn the _____ of each atom & the e- of the other. when the 2 atoms are at an optimal distance from each other, this attraction is greater than e- - e- repulsion and the energy of the system is at a(n) ____.

covalent; nucleus; minimum

what does the prefix n in the name n-pentane indicate about the compound a) the C chain can be of diff lengths b) the C chain is branched c) the C chain contains a N atom d) the C chain is unbranched

d

what is the correct IUPAC name for the compound (CH3)2CCHClCH(CH3)2? a) 2,2,4-trimethyl-3-chloro-pentane b) 3-chloro-2,4,4-trimethylpentane c) 2,4,4,-trimethyl-chloropentane d) 3-chloro-2,2,4-trimethylpentane

d

as branching of alkanes increases, the heat of combustion _____

decreases

according to molecular orbital theory of simple diatomic molecules, the # of bonding molecular orbitals is ____ to # of nonbonding orbitals

equal

the higher the molecular weight of the alkane, the ___ the BP

higher

antibonding orbitals

higher in energy - nodes btwn bonding nuclei

Alkanes

hydrocarbons in which all bonds are SINGLE bonds

Nonpolar molecules such as alkanes are not soluble in water, because the _______ bonding in water is too strong to be disrupted by the weak attraction between the alkane and water molecules. The exclusion of nonpolar molecules from water is called the _______ effect

hydrogen; hydrophobic

forces ______ as distance btwn 2 hydrogens _____

increase; decreases

in-phase orbital overlap ____ probability of finding an e- in the region btwn the 2 nuclei where it feels the attractive force of both of them

increases

for alkanes, the amnt of heat released _____ as the # of C atoms in the compound increases but _______ as the amnt of branching increases for the same # of C atoms.

increases; decreases

the more stable an alkane is to start with, the _____ the amount of energy released when that compound undergoes combustion

lower

the more stable the compound, the ______ the energy and thus the ____ the heat of combustion

lower; lower

the simplest & most abundant alkane

methane (CH4)

alkanes: BP increases with

molecular weight

pi bond

multiple bonds derived from side-on overlap of 2p orbitals

the C-C & C-H bonds of alkanes are ____. as a result, alkanes exhibit only _____ intermolecular forces, causing their BP to be lower than alcohols of similar size.

nonpolar; induced dipole-induced dipole

valence bond model describes bonding as the

overlap of 2 filled orbitals

in an organic reaction, the process of _____ results in an increase in the # of C-Z bonds or a ____ in the number of C-H bonds, where Z is an element with a greater electroneg than H

oxidation; decrease

to name a simple cycloalkane, the # of C atoms int he ring gives the ____ name & the prefix ____ is added before this part of the name

parent; cyclo

half-filled 2p orbitals have their axes perpendicular to the framework of sigma bonds of the molecular & overlap in a side-by-side manner to give a _____ bond

pi

a bond formed by side-to-side overlap of 2 p orbitals is called a ____ bond. the less efficient overlap makes this type of bond ____ and more reactive than a sigma bond.

pi; weaker

characteristic feature of valence bond theory

pictures a covalent bond btwn 2 atoms in terms of an in-phase overlap of a half-filled orbital of 1 atom w/ a half-filled orbital of the other i.e. H2 both have e- in a 1s orbital so that their orbitals overlap to give a new orbital associated w/ both of them

what information does the prefix, suffix, & parent name give

prefix: identity, location & # of substituents suffix: functional group/class of compound parent name: # of C atoms in the longest continuous C chain

each C-H bond of CH4 is a ____ bond in which a half-filled 1s orbital of H overlaps w/ a half-filled sp3 orbital of C along a line drawn between them

sigma

an alkane is a hydrocarbon that contains only C-C ___ bonds. each C atom in the structure is singly bonded to 4 other atoms & possesses ____ geometry

sigma, tetrahedral

the triple bond in the sructure shown is formed by the overlap of a(n) ___ orbital on the C w/ a(n) ____ orbital on the N to forme the sigma bond. the pi bonds are formed by the overlap of 2 pairs of ____ orbitals.

sp, sp , p

each C atom in an alkane is ___-hybridized

sp3

what type of orbitals do the unshared e- pairs of O occupy in water molecule? a) sp2 b) sp3 c) p d) s

sp3

in order to form 4 hybrid bonding orbitals of equal energy, 1 s & 3 p orbitals from the valence shell of a C atom "mix" to form 4 ____ hybrid orbitals. These orbitals are equal in shape & energy & are arranged in a ____ geometry.

sp3; tetrahedral

the hybridization of 1 s & 1 p orbital will result in the formation of 2 ___ hybrid orbitals. this will leave ___ unhybridized p orbital (s) which are at right angles to the hybrid orbitals

sp; 2

a momentary change in the e- density surrounding an atom/molec causes it to have a _____ dipolar even if it's not normally polar. this induces a similar effect in a nearby molec/atom, & there will be a weak attraction btwn the 2 particles as a result. these weak interactions are called van der _____ forces

temporary; waals

since ammonia & water have ___ arrangement of e- pairs, then the hybridization of the N & O in both molecular is _____.

tetrahedral; sp3

the axes of the sp3 orbitals point ____ the corners of a tetrahedron

toward