Exam 3

Question 1

how are discrete line spectras produced

Answer 1

exciting a gas at a low partial pressure

Question 2

formula for energy absorbed/emitted

Answer 2

hc/wavelength

Question 3

quantized definition

Answer 3

a system is limited to specific energy values

Question 4

when is a photon emitted

Answer 4

when an e- transitions from a ground state to an excited state

Question 5

energy of a photon formula

Answer 5

h * v

Question 6

relationship between electron energy and distance from nucleus

Answer 6

as one increases, so does the other

Question 7

what is coulomb’s potential?

Answer 7

attractive force between a positive nucleus and an electron

Question 8

important features of all orbital models

Answer 8

energies of electrons are quantized
electron energy increases with distance from nucleus
discrete energies (lines) in spectra come from quantized electronic energies

Question 9

constructive intereference

Answer 9

peaks and troughs coincide to amplify

Question 10

destructive interference

Answer 10

peaks and troughs conflict, cancels out

Question 11

how to obtain probability density

Answer 11

square the wavefunction

Question 12

principle quantum number

Answer 12

n
location of energy level/shell number

Question 13

angular momentum quantum number

Answer 13

l
defines shape of orbital
any value from o to n-1

Question 14

magnetic quantum number

Answer 14

m1
defines z component of l
ex. l = 1, m1 = -1, 0, +1

Question 15

is absorption/emission of light endo or exothermic?

Answer 15

absorption: endothermic
emission: exothermic

Question 16

wavefunction squaured …

Answer 16

probability of finding an electron at a given point near the position

Question 17

radial distribution

Answer 17

total probability of finding an electron at a given distance (r) from the nucleus
- r increases with surface area

Question 17

describe the electron density graph of the 1s orbital

Answer 17

starts high, goes lower, no nodes

Question 18

describe the electron density graph of the 2s orbital

Answer 18

starts high, one node, one peak

Question 19

describe the electron density graph of the 3s orbital

Answer 19

starts high, 2 nodes, one large peak, one smaller peak

Question 20

describe the radial distribution graph of the 1s orbital

Answer 20

starts low, not at zero, one massive peak

Question 21

describe the radial distribution graph of the 2s orbital

Answer 21

starts low, closer to zero, one node, two peaks second is larger than the first

Question 22

describe the radial distribution graph of the 3s orbital

Answer 22

starts low, closer to zero, two nodes, three peaks getting progressively larger

Question 23

orbitals in the nth energy level

Answer 23

n^2

Question 24

#electrons in the nth energy level

Answer 24

2n^2

Question 25

#orbitals in the l-subshell

Answer 25

2l + 1

Question 26

how many electrons can each orbital hold

Answer 26

2

Question 27

what is the pauli exclusion principle

Answer 27

no two e- can have the same set of 4 quantum numbers

Question 28

what l values correlate to subshells?

Answer 28

l = 0, s l = 1, p l = 2, d l = 3, f

Question 29

difference between surface nodes and radial nodes

Answer 29

surface nodes (planar) are found at the original of the radial graphs, while radial nodes are not

Question 30

total nodes (surface + radial) =

Answer 30

n - 1

Question 31

#surface/planar nodes =

Answer 31

l

Question 32

diamagnetic definition

Answer 32

all e- are paired

Question 33

paramagnetic definition

Answer 33

at least one unpaired e-

Question 34

isoelectronic definition

Answer 34

same #e-

Question 35

isovalent definition

Answer 35

same #valence e-

Question 36

what are degenerate orbitals

Answer 36

having the same energy

Question 37

what is effective nuclear charge

Answer 37

Zeff - strength of the e- – nucleus interaction - = Z (atomic number) - # core e- - increases from left to right - increases as electron subshell level decreases

Question 38

what are the common periodic table trends

Answer 38

- atomic radii (size) increases from right to left and down - ionization energy (to remove an e- from a gaseous atom) increases left to right and up - electron affinity (energy change with addition of an e- to a neutral gas) more negative left to right and up - ionic radii --> anions are larger than cations

Question 39

definition of electronegativity

Answer 39

the degree to which an atom can attract an e- in a bond

Question 40

nonpolar covalent bond

Answer 40

equal sharing of e- between two identical nonmetal elements

Question 41

polar covalent

Answer 41

unequal sharing of e- between two nonmetals small electronegativity difference

Question 42

ionic

Answer 42

metal + nonmetal e- are transferred to nonmetal large electronegativity difference

Question 43

as electronegativity increases, what happens to the following? - bond polarity - ionic character - covalent character

Answer 43

- increase - increase - decrease

Question 44

what is bond order

Answer 44

essentially, number of bonds = # bonds/ # bond locations

Question 45

as bond order increases, what happens to the following? - bond strength - bond length - bond dissociation energy

Answer 45

- increase - decrease - increase

Question 46

what is formal charge

Answer 46

charge on an atom as determined by lewis dot structure = #valence e- - #e- shown around atom in lewis dot structure

Question 47

what is needed for a lewis dot structure to contribute most in resonance?

Answer 47

- smaller (ideally 0) formal charges - more zeros for formal charges - if formal charges are equal, the structure with the more negative formal charge on the more electronegative atom

Question 48

electron pair geometry versus molecular geometry

Answer 48

EPG: - geometry including all domains (including lone pairs) MG: - refers to actual arrangement of atoms - does not include lone pairs

Question 49

what is a dipole moment? when does it cancel?

Answer 49

dipole moment: measure of molecular polarity - cancels when bond vectors cancel out --> nonpolar molecule - when bond vectors create a net vector --> polar molecule

Question 50

relate VSEPR and polarity

Answer 50

(#atoms, #lone pairs) POLAR: (2,1) (3,1) (2,2) (4,1) (3,2) (5,1) NONPOLAR: (2,0) (3,0) (4,0) (5,0) (2,3) (6,0) (4,2) AND all atoms around central atom are the same

Question 51

are hydrocarbons polar or nonpolar?

Answer 51

nonpolar

Question 52

are binary atom molecules polar or nonpolar?

Answer 52

nonpolar

Question 53

are X-Y molecules polar or nonpolar?

Answer 53

polar

Question 54

where do sigma bonds lie

Answer 54

directly between the two nuclei of atoms

Question 55

what type of bond is in all single, double, or triple bond?

Answer 55

sigma

Question 56

compare sigma bonds and pi bonds

Answer 56

SIGMA - can rotate - symmetrical - stronger PI - cannot rotate - weaker

Question 57

where do pi bonds lie

Answer 57

above and below the internuclear axis

Question 58

what is required to make a pi bond?

Answer 58

two p-atomic orbitals