Deck 2: Chemical Foundations I: Chemical Energy and Intermolecular Forces

Question 1

C-C double bonds resist rotation about their C-C axis because

A) Rotation breaks the overlap of the pi orbitals which forms part of the double bond
B) The substituted groups sterically hinder each other
C) The double bond soaks up thermal energy
D) This isn't true: double C-C bonds rotate nearly as freely as single C-C bonds
E) Their configuration is locked by multiple sigma bonds formed between the two carbons

Answer 1

A

Question 2

Which of the following is NOT TRUE of chemical bonds

A) Bo nd leng ths and ang les a re fixe d an d rig id
B) Bond lengths are typically about 0.1-0.2 nm
C) Bond energies range from about 200 to 460 kj mol-1
D) Bond lengths are shorter in double bonds than single bonds
E) Bond energy is expressed as enthalpy differences

Answer 2

A

Question 3

Hydrogen bonds can occur between the following pairs of atoms

A) O and O
B) N and C
C) O and C
D) N and S
E) None of the above

Answer 3

A

Question 4

Polar bonds occur between atoms

A) with ab out th e sa m e elec trone gativity
B) with the grea test d iffere nce in elec trone gativity
C) with inte rmed iate differences in e lectroneg ativity
D) displaying only sp3 hyb rid izat ion for m ole cu lar orb itals
E) displaying only sp2 hyb rid izat ion for m ole cu lar orb itals
1

Question 5

Ele ctr on eg ativ ity

A) Is the ability of an atom to attract shared electrons
B) Is based on a relative scale with oxygen as the m ost electronegative
C) Differences must be small to generate ionic solutes
D) Differences must be small to generate polar bonds
E) Is irrelevant to bond type

Question 6

Two chem icals showing cis-trans isomerism differ in

A) The elemental composition of the compounds
B) The arrangement of atoms around a double bond
C) The connectivity of atoms - which atoms are bonded to which
D) They are mirror images of each other
E) Having widely different bond energies

Question 7

Hydr oge n bo nds are u sua lly about

A) The sam e strength as a C-C bond
B) 0.2 - 0.5 times the strength of a C-C bond
C) 0.02-0.1 times the strength of a C-C bond
D) Less than 0.02 times the strength of a C-C bond
E) 0.5-0.7 times the strength of a C-C bond

Question 8

Str uc tur al is om er s d iffe r in

A) The elemental composition of the compounds
B) The arrangement of atoms around a double bond
C) The connectivity of atoms - which atoms are bonded to which
D) They are mirror images of each other
E) They have widely different bond energies

Question 9

Attractive forces between molecules include all of the following EXCEPT

A) Hydrogen bonding
B) Dipole-dipole interaction
C) London dispersion forces
D) Coulombic attraction from ionized groups
E) Inte rm olec ular elec tron ic orb itals

Question 10

London dispersion forces

A) Refer to attraction of molecules due to permanent dipoles
B) Are long-range forces produced by ionic charge separation
C) Are short-range forces caused by synchronized induced dipoles
D) Are short-range forces caused by shielded coulombic attraction
E) W ere u sed to pro tect th e citizen s of E ngla nd in W orld W ar II

Question 11

In a n e lec tric field

A) pe rm an en t dip oles w ill exp erien ce a torq ue atte m ptin g to align the m w ith th e field
B) Dipole mom ent is reduced
C) Permanent dipole moments are created
D) Dipole-dipole interactions are masked
E) A dip ole ca n be induc ed p ropo rtiona l to the s qua re of the e lectric fie ld inten sity

Question 12

Which o f th e fo llow ing pa irs of c om po un ds is a n e xa m ple of o ptic al is om er ism :

A) O leic ac id a nd ela dic ac id
B) Glyce ralde hyde -3-p hos pha te an d dihyro xyac eton e ph osp hate
C) D-glucose and fructose
D) D-alanine and L-alanine
E) Propanol and isopropanol

Question 13

Which of the following elements is NOT used as a cofactor in enzymes?

A) Mn
B) Zn
C) Cu
D) Se
E) Ti

Question 14

Which o f th e fo llow ing ele m en ts is us ed as a p hys iolo gic ally a ctiv e c om po ne nt o f th e b od y?

A) Cd
B) Hg
C) Os
D) I
E) Te

Question 15

Which of the following elements has no known use in the body?

A) Cl
B) I
C) Mo
D) Zn
E) Ga

Question 16

Atom s with the g reate st diffe renc e in ele ctron ega tivity

A) Form non-polar covalent bonds
B) Form polar covalent bonds
C) Form ionic bonds
D) Don't bond together
E) Form hydrogen bonds