Chapter 5 & 6

Question 1

— equal but alternate Lewis Structures

Answer 1

Resonance Structures

Question 2

Lewis Dot Structures Rules

Question 3

— for an atom in a molecule or platonic ion, charge =
# of valence electrons — 1/2 # bonding electrons — # of nonbonding electrons

Answer 3

Formal Charge

Question 4

Best Resonance Structure Rules

Answer 4

1) minimize formal charges
2) like formal charges should be far apart
3) opposite charges on adjacent atoms

Question 5

Octet Rule Exceptions

Answer 5

1) Odd # of electrons — normally unstable
2) < octect
3) > octect — common for 3rd row elements & higher rows

Question 6

— ability of atoms in bond to attract bonding electrons to itself

Answer 6

Electronegativity (x)

Question 7

— in simple molecules (Cl2, N2, O2), electrons in bonds are shared equally

Answer 7

Nonpolar Bond

Question 8

— intermediate case between ionic & covalent bond (HF)

Answer 8

Polar Covalent Bond

Answer 9

Pauling Electronegativity Values

Question 10

— degree of polarity of a molecule

Answer 10

Dipole Moment

Question 11

— 1 molecule whose centers of (+) & (-) charge do not coincide

Answer 11

Polar Molecule

Question 12

— minimizes repulsion between electrons pairs

Answer 12

VSEPR
Valence Shell Electron Pair Repulsion model

Question 13

3 steps in VSEPR method:

Answer 13

1) sketch Lewis dot structure
2a) count total # of electron pairs around central atom
2b) arranged electron pairs so as to minimize repulsion’s
3) (Angular Arrangement of bonded atoms) — describe molecular geometry in terms of bonding pairs of electrons

Question 14

— repel electrons better than bonding pairs

Answer 14

Nonbonding pairs

Question 15

— energy change required to break a bond in one mole of gaseous substance

Answer 15

Bond (Dissociation) Energy

Question 16

The stronger the bond, the
two answers

Answer 16

— the greater the dissociation energy
— the shorter the bond length

Question 17

— build up of electron density between two nuclei
— overlap of valence atomic orbital of one atom with that of another atom

Answer 17

Valence Bond Theory

Question 18

— has its electrons density concentrated symmetrically about the internuclear axis
— end to end bonding

Answer 18

Sigma Bond

Question 19

— overlap regions above & below the internuclear axis (nodal planes)

Answer 19

Pi Bonds

Question 20

Single Bonds

Answer 20

— 1 sigma bond

Question 21

Double Bonds

Answer 21

— 1 sigma bond
— 1 pi bond

Question 22

Triple Bonds

Answer 22

— 1 sigma bond
— 2 pi bonds

Question 23

— “mix” two or more atomic orbitals & make the same # of hybrid orbitals

Answer 23

Hybrid Orbitals

Question 24

— apparent in molecular orbitals theory
Ex) Benzene ( C6H6)

Answer 24

Delocalization

Question 25

— similar to atomic orbitals but for molecules, will fill from lowest to highest in energy to get electron configurations

Answer 25

Molecular Orbital Theory (M.O. Theory)

Question 26

— approximates molecular orbitals

Answer 26

LCAO
Linear Combinations of Atomic Orbitals

Question 27

— orbitals with lower energy in molecular orbitals theory
— Stabilized

Answer 27

Bonding Orbitals

Question 28

— orbitals with higher energy in molecular orbitals theory
— Destabilized

Answer 28

Anti-Bonding Orbitals

Question 29

Bond Order Formula

Answer 29

Bond Order = 1/2 ( # of bonding electrons — # of anti-bonding electrons)

Question 30

— unpaired electrons present
— attracted by magnetic field
— material appears to weigh more

Answer 30

Paramagnetic

Question 31

— no unpaired electrons
— weakly repelled by magnetic field
— material appears to weigh less

Answer 31

Diamagnetic

Question 32

— same # of electrons with electrons configurations

Answer 32

Isoelectronic Series