Exam Three Flashcards
Pi/Sigma bonds within a double bond:
one pi bond and one sigma
Pi/Sigma bonds within a triple bond:
two pi bonds and one sigma
Which elements can have an expanded octet (provide example for each.
- phosphorus (PCl5)
- sulfur (SF6)
- chlorine (ClF3)
- sulfate ion
- sulfate oxides
What compounds can have a deficient octet?
- BeCl2
* *central atom has 2 sigma bonds - BF3
* *central atom has 3 sigma bonds
What compound have a weird octet?
NO2
**due to lone electron
Class of a linear geometry:
AX2 or AX2E3
Example of linear geometry (3):
BeF2, HCN, CO2
Ideal bond angle of a linear geometry:
180
Class of trigonal planar:
AX3
Ideal bond angle of trigonal planar:
about 120
Class of bent:
AX2E or AX2E2
What do lone pairs do to the bond angle?
causes deviation, angle will be less than the ideal value
Tetrahedral electron group arrangement can have how many shapes?
3
Class of tetrahedral:
AX4
Class of trigonal pyramidal:
AX3E
Ideal bond angle of tetrahedral arrangments:
about 109.5
Trigonal bipyramidal electron group arrangement can have how many shapes?
4
Class of trigonal bipyramidal:
AX5
Class of seesaw:
AX4E
Class of t-shape:
AX3E2
Ideal bond angle of trigonal bipyramidal arrangments:
about 120 and 90
- *t-shaped is 90
- *linear is 180
Octahedral electron group arrangement can have how many shapes?
3
Class of octahedral:
AX6
Class of square pyramidal:
AX5E
Class of square planar:
AX4E2
Ideal bond angle of octahedral arrangement:
about 90
Period(s) […] can form more than four bonds.
3-6
Formal charge:
valence - sticks - dots
As you go L to R across the periodic table, the atomic size…
decreases
**nucleus to electron attraction (Zeff)
As you go down the periodic table, the atomic size…
increases
**adding more orbitals
Down a group […] dominates due to […].
Across a period […] dominates because […] remains the same and electrons pull closer to […]..
n (quantum number); electron shielding;
Zeff (effective nuclear charge); electron shielding; the nucleus
What is electron shielding? How does this affect the periodic trend?
inner layers of electrons shield the outer electrons
Down a transition series, atomic size […] from Period 4 to 5 and […] from 5 to 6.
increases slightly; none
Across a transition series, atomic size […] through the first two or three elements.
shrinks
After the first 2/3 elements in the transition series, the atomic size…
remains constant
Size of V (23) compared to Zn (30):
same
**transition metals going across a series remain constant
Atoms with a low IE tend to form […] while those with a high IE tend to form […] (except for […]).
cations; anions; noble gases
Ionization energy:
requirement to completely remove 1 mol of electrons from 1 mol of atoms/ions
Ionization energy is to overcome the […].
electrostatic attraction
As size decreases, it takes […] energy to remove an electron.
more
Electronegativity is inversely related to […]. So across the periodic table, EN […] while down the table, EN […].
atomic size; increases; decreases
Pauli exclusion principle:
no two electrons in the same atom can have the same four quantum numbers
Consequence of exclusion principle:
an atomic orbital can hold a max of two electrons, which must have opposing spins
**unique value of ms
A higher nuclear charge (Z) increases […] and this lowers […] which stabilizes the atom.
nucleus-electron attraction; sublevel energy
Nuclear charge stabilizes the atom and make is difficult to….
remove an electron
** harder to remove electron from Li2+ compared to H
Effective nuclear charge is due to…
shielding
Hund’s rule:
when orbitals of equal energy are available, the electron configuration of lowest energy has the max number of unpaired electrons with parallel spins
Which electron configurations are exclusions to Aufbau’s principle? What occurs? Are these still stable?
copper and chromium
to fill d sublevel, an electron from the s sublevel is taken
these are stable (low in energy)
Quantum number “n” represents:
principle energy level; the number matches the outermost s and p sublevels
Ionization generally […] across a period and […] down a group.
increases; decreases
Two exceptions to the IE trend:
- Group 3 (B and Al) dips because they easily remove an electron to conform to a stable configuration
- Group 6 (O and S) dips because they easily to obtain half filled orbital
Electron affinity:
energy release/required when an electron is added to a neural atom
The first electron affinities are […].
negative
EA across the periodic table […], down the periodic table […].
increases; decreases
Species with unpaired electrons exhibits…
paramagnetism
Paramagnetism:
attracted by an external magnetic field
Species with all of its electrons paired exhibits…
diamagnetism
Diamagnetism:
not attracted (slightly repelled) by the magnetic field
Heisenberg’s uncertainty principle:
impossible to know simultaneously the position and momentum of a particle
Lyman is […] when H transmission goes to […].
UV radiation; n=1
Balmer is […] when H transmission goes to […].
visible; n=2
Paschen is […] when H transmission goes to […].
infrared; n=3
Wavelength of Lyman series:
90 to 125
Wavelength of Balmer series:
400 to 660
Wavelength of Paschen series:
1200 to 1900
Albert Einstein contribution:
proposed that light itself is particulate, quantized into tiny “bundles” of energy
**later called photons
Rydberg equation:
predicts position and wavelength of any line in a given series
De Broglie contribution:
if energy is particle-like, perhaps matter is wavelike
De Broglie equation:
- wavelength = h/(mu)
- wavelength = h/p
- *h = planks constant
- *m = mass
- *u = speed
- *p = momentum
Plank:
energy is quantized
Bohr:
energy of atoms is quantized; photon is emitted when electron changes orbit
Davisson/Gemer:
electron beam is diffracted by metal crystal (helps de Broglie)
Compton:
photon’s wavelength increases (momentum decreases) after colliding with electron
Einstein/de Broglie:
mass and energy are equivalent: particles have wavelength and photons have momentum (help Compton)
Quantum number “l” represents:
angular momentum/shape of the orbital
Magnetic quantum number (ml):
orientation; is the total number of orbitals in that energy level
If l = 0, ml will be…
0
If l = 1, ml will be…
-1, 0, 1
If l = 2, ml will be…
-2, -1, 0, 1, 2
If l = 3, ml will be…
-3, -2, -1, 0, 1, 2, 3
What does ms represent:
spin of electron (+,- 1/2)
Isoelectronic series:
given ions have the same number of electrons (noble gas configuration)
Ions without a noble gas configuration create:
1, pseudo-noble gas configuration
2. inert pair configuration
Pseudo-noble gas configuration:
empties out its highest energy level
Inert pair configuration:
metal atoms loses just its np electrons (stable with just ns)
Isoelectric series and atomic radius:
radius increases from right to left and down a period
