Bonding and Intermolecular Forces - Thermodynamics

Question 1

How to calculate formal charge

Answer 1

formal charge = valence electrons - sticks (bonds) - bonds (lone pairs)

Question 2

where do you place positive charges

Answer 2

on the less electronegative atoms

Question 3

where do you place negative charges

Answer 3

on the more electronegative atoms

Question 4

2 groups

Answer 4

• sp

Question 5

3 groups

Answer 5

• sp2

Question 6

4 groups

Answer 6

• sp3

Question 7

sp2 hybridization with no lone pairs

Answer 7

trigonal planar

Question 8

sp2 hybridization with one lone pair

Answer 8

bent

Question 9

sp3 hybridization with no lone pairs

Answer 9

tetrahedral

Question 10

sp3 hybridization with one lone pair

Answer 10

trigonal pyramidal

Question 11

sp3 hybridization with 2 lone pairs

Answer 11

bent

Question 12

sp hybridization with no lone pairs

Answer 12

linear

Question 13

the strength of a chemical bond is dependent upon

Answer 13

• more electrons shared = stronger bond

- shorter distance between atoms = stronger bond

Question 14

stronger bonds

Answer 14

• higher bond dissociation energies
• more energy to break the bond
• always an endothermic process

Question 15

types of bonds

Answer 15

• intramolecular (nuclear)

- intermolecular

Question 16

intramolecular (nuclear bonds)

Answer 16

• covalent
• coordinate covalent
• metallic

Question 17

covalent

Answer 17

• sharing of electrons
• polar
• nonpolar

Question 18

polar covalent

Answer 18

• 2 atoms share valence electrons
• different electronegativity - unequal sharing
• dipole moment (partial charges)

Question 19

nonpolar covalent

Answer 19

• 2 atoms share valence electrons

- similar electronegativity = equal sharing

Question 20

coordinate covalent bond

Answer 20

• metal/lewis acid - acceptor
• ligand/lewis base - donor
• ligand brings both electrons for bond.

Question 21

metallic bond

Answer 21

• sea of free floating electrons

- metals like to lose electrons

Question 22

ionic bond

Answer 22

• one gives other takes electrons
• very different electronegativity
• atoms with formal charges
• cation and anion
• Na+ Cl-

Question 23

Intermolecular forces

Answer 23

• Hydrogen bond
• Dipoles
• London Dispersion (Van Der Waals)

Question 24

Dipoles

Answer 24

• ion-dipole
• dipole-dipole
• dipole-induced dipole
• easily cleaved

Question 25

hydrogen bond

Answer 25

• strong intermolecular forces
• produced between very polar molecules
• 2 criteria
• FON w/ lone pairs
• FON with hydrogen

Question 26

ion-dipole

Answer 26

• polar molecule + ion

- higher charged ion and more polar molecule make for stronger force

Question 27

dipole-dipole

Answer 27

• polar covalent + polar covalent

- partial charges attract

Question 28

dipole-induced dipole

Answer 28

• polar covalent + nonpolar covalent
• partial charge on one causes temporary partial charge on the other
• very short lived so very easily cleaved

Question 29

London dispersion

Answer 29

• nonpolar molecules
• all molecules
• instantaneous induced dipoles
• electron cloud is deformed by collisions that produce temporary but small dipoles

Question 30

enthalpy

Answer 30

• energy stored within chemical bonds or any attractive force

Question 31

high energy reactants and low energy products

Answer 31

• exothermic

- ΔH < 0

Question 32

low energy reactants and high energy products

Answer 32

• endothermic

- ΔH > 0

Question 33

breaking bonds

Answer 33

• exothermic

Question 34

forming bonds

Answer 34

• endothermic

Question 35

enthalpy of formation

Answer 35

• the amount of energy associated with forming one mole of a compound from its constitutive elements in their standard states

Question 36

Δ H of a standard state

Answer 36

0

Question 37

Hess’s law

Answer 37

• combine two or more reactions and to find their total

Question 38

reversing the direction of a reaction

Answer 38

changes the sign of ΔH and ΔS

Question 39

changing the stoichiometric coefficient of a reaction

Answer 39

you must scale the value of the ΔH or ΔS for the reaction

Question 40

Entropy

Answer 40

• the measure of disorder/potential randomness
• increasing number of particles
• changing from solid to liquid to gas
• increasing the temperature
• increasing volume

Question 41

Gibb’s free energy

Answer 41

• energy available to do work

- ΔG = ΔH-TΔS

Question 42

spontaneous process

Answer 42

• exergonic

- high energy reactants, low energy products

Question 43

nonspontaneous process

Answer 43

• endergonic

- low energy reactants, high energy products

Question 44

core electrons

Answer 44

• do nothing!!