Bonding and Intermolecular Forces

Question 1

single bond

Answer 1

a bond formed from two electrons

Question 2

how many electrons are involved in a double bond?

Answer 2

4

Question 3

how many electrons are involved in a triple bond?

Answer 3

6

Question 4

resonance hybrid

Answer 4

the “average” of possible resonance structures

Question 5

bond dissociation energy (BDE)

Answer 5

the energy required to break a bond homolytically

Question 6

homolytic bond cleavage

Answer 6

one electron of the bond being broken goes to each fragment of the molecule

Question 7

heterolytic bond cleavage (dissociation)

Answer 7

both electrons of the electron pair that make up the bond end up the same atom

Question 8

what does homolytic bond cleavage form?

Answer 8

radicals (has BDE)

Question 9

what does heterolytic bond cleavage form?

Answer 9

ions

Question 10

are the energies of heterolytic and homolytic bond breaking similar?

Answer 10

no, completely different energies

Question 11

for similar bonds, the higher the bond order…

Answer 11

the shorter and stronger the bond

Question 12

bond order

Answer 12

the number of bonds between adjacent atoms

Question 13

comparisons of bond length and BDE should only be made for:

Answer 13

similar bonds

Question 14

the greater the s-character in the hybrid orbitals:

Answer 14

the shorter the bond (s-orbitals are closer to the nucleus)

Question 15

when comparing the same types of bonds, the longer the bond….

Answer 15

the weaker it is, the shorter the bond, the stronger it is

Question 16

covalent bond

Answer 16

formed between atoms when each contributes one or more of its unpaired valence electrons so that the electrons are shared by both atoms to help complete both octets

Question 17

polarity

Answer 17

when a molecule is partially negative on one end and partially positive on the other end

Question 18

dipole moment

Answer 18

the polarity present in a polar molecule

Question 19

what constitutes a polar bond?

Answer 19

if the electron density between the two nuclei is uneven

Question 20

the greater the difference in electronegativity of the bonding atoms…

Answer 20

the more uneven the electron density and the greater the dipole moment

Question 21

what constitutes a nonpolar bond?

Answer 21

the electron density between the two nuclei is even

Question 22

coordinate covalent bond

Answer 22

when one atom donates both of the shared electrons in a bond

Question 23

what are two other synonyms for Lewis base?

Answer 23

ligand or nucleophile

Question 24

what’s another word for Lewis acid?

Answer 24

electrophile

Question 25

what happens to the electrons in the breaking of a coordinate covalent bond?

Answer 25

the electrons that come from the ligand will leave with that ligand

Question 26

ionic bond

Answer 26

cation and anions held together by electrostatic attraction

Question 27

in ionic bonds, what is the strength of the bond proportional to?

Answer 27

the charges on the ions

Question 28

in ionic bonds, what is the strength of the bond inversely proportional to?

Answer 28

the distance between ions, or the ionic radii

Question 29

valence shell electron-pair repulsion theory (VSEPR)

Answer 29

since electrons repel one another, electron pairs, whether bonding or nonbonding, attempt to move as far apart as possible

Question 30

molecular geometry

Answer 30

the shape of a molecule

Question 31

how are sigma bonds formed?

Answer 31

formed by the end-to-end overlap of one hybridized orbital (or an s orbital in the case of hydrogen) from each of the two atoms participating in the bond

Question 32

sigma bond

Answer 32

consists of two electrons that are localized between two nuclei

Question 33

how are pi bonds formed?

Answer 33

formed by the proper, parallel, side-to-side alignment of two unhybridized p orbitals on adjacent atoms

Question 34

pi bond

Answer 34

composed of two electrons that are localized to the region that lies on opposite sides of the plane formed by the two bonded nuclei and immediately adjacent atoms, not directly between the two nuclei

Question 35

intermolecular forces

Answer 35

the relatively weak interactions that take place between neutral molecules

Question 36

ion-dipole forces

Answer 36

polar molecules are attracted to ions

Question 37

dipole-dipole forces

Answer 37

attraction between the positive end of one polar molecule and the negative end of another polar molecule

Question 38

what is the strongest dipole-dipole force?

Answer 38

hydrogen-bonding

Question 39

dipole-induced dipole force

Answer 39

a permanent dipole in one molecule induces a momentary dipole in a neighbouring nonpolar molecule

Question 40

London dispersion forces

Answer 40

an instantaneous dipole in a nonpolar molecule may induce a dipole in a neighbouring nonpolar molecule: weak and transient interaction

Question 41

how could LDF forces increase?

Answer 41

if size of molecule and its number of electrons increases-this increases partial charge of induced dipole

Question 42

van der Waals forces

Answer 42

collectively refers to dipole forces, hydrogen bonding, and London forces

Question 43

what is required for hydrogen bonding to occur?

Answer 43

1) a molecule must have a covalent bond between H and either N, O, or F 2) a molecule must have a lone pair of electrons on an N, O, or F atom

Question 44

vapour pressure

Answer 44

the pressure exerted by the gaseous phase of a liquid that evaporated from the exposed surface of the liquid

Question 45

what is the relationship between a substance's intermolecular forces and vapour pressure?

Answer 45

weaker intermolecular forces=higher vapour pressure, more easily evaporated

Question 46

volatile

Answer 46

easily vaporized liquids

Question 47

aside from intermolecular forces, what influences vapour pressure?

Answer 47

temperature: increased temperature of substance=increased vapour pressure

Question 48

ionic solid

Answer 48

held together by the electrostatic attraction between cations and anions in a lattice structure; the bonds that hold all the ions together in the crystal lattice are the same as the bonds that hold each pair of ions together

Question 49

network solid

Answer 49

atoms are connected in a lattice of covalent bonds (all interactions between atoms are covalent bonds); the intermolecular forces are identical to the intramolecular forces

Question 50

metallic solids

Answer 50

a covalently bound lattice of nuclei and their inner shell electrons surrounded by a "sea" of electrons

Question 51

conduction electrons

Answer 51

freely roaming valence electrons in metallic solids that are not bound to any particular atom and is free to move throughout the lattice, allows for excellent conduction of electricity and heat

Question 52

molecular solids

Answer 52

the particles at the lattice points of a crystal of a molecular solid are molecules held together by one of the three types of intermolecular interactions (H bond, dipole, LDF)