CHM 3610 Intermediate Inorganic Chemistry - Lecture 19 Review

Flashcards covering key intermediate inorganic chemistry concepts from Lecture 19, including coordination chemistry, isomerism, symmetry point groups, main group chemistry, crystallography, and X-ray diffraction.

Lanthanoid Contraction

The decrease in atomic radius from La to Er across the lanthanoid series caused by poor shielding of the increasing nuclear charge by $4f$ electrons, which draws outer electrons inward.

Zr/Hf Size Similarity

A structural consequence of the lanthanoid contraction where poor shielding by filled $4f$ electrons in Hf offsets the expected group size increase, making 5d Hf nearly identical in radius to 4d Zr.

Methane Symmetry ($T_d$)

A point group possessing four $C_3$ proper rotation axes passing through the C–H bonds and three $C_2$ axes passing through opposite edge midpoints of the tetrahedron.

Ammonia Symmetry ($C_{3v}$)

A trigonal-pyramidal point group characterized by one $C_3$ axis through the N atom and three vertical mirror planes ($\sigma_v$), each containing one N–H bond.

$\text{ClF}_4^+$ and $\text{ClF}_4^-$ Geometries

VSEPR molecular geometries corresponding to seesaw ($\text{AX}_4\text{E}$) for $\text{ClF}_4^+$ with one lone pair, and square planar ($\text{AX}_4\text{E}_2$) for $\text{ClF}_4^-$ with two lone pairs.

$\text{BrF}_3$ and $\text{XeF}_4$ Geometries

VSEPR molecular geometries corresponding to T-shaped ($\text{AX}_3\text{E}_2$) for $\text{BrF}_3$ with two lone pairs, and square planar ($\text{AX}_4\text{E}_2$) for $\text{XeF}_4$ with two opposite lone pairs.

Tridentate Ligand

A chelating ligand, such as diethylenetriamine ($\text{H}_2\text{NCH}_2\text{CH}_2\text{NHCH}_2\text{CH}_2\text{NH}_2$), that coordinates to a single metal center through three donor atoms to form chelate rings.

Bidentate Ligand

A chelating ligand, such as ethylenediamine ($\text{en}$), that supplies two donor atoms to the same metal ion; three such ligands generate a coordination number of 6 in $[\text{Co(en)}_3]^{3+}$.

Ionization Isomerism

Isomerism resulting from the mutual exchange of a coordinated ligand in the inner coordination sphere with an uncoordinated counterion (e.g., $[\text{CoBr(NH}_3)_5]\text{SO}_4$ and $[\text{Co(SO}_4\text{)(NH}_3)_5]\text{Br}$).

Linkage Isomerism

Isomerism arising when an ambidentate ligand, such as $\text{NO}_2^-$, binds to the same central metal via different donor atoms (e.g., N-bound nitro versus O-bound nitrito).

Low-Spin Octahedral $[\text{Co(CN)}_6]^{3-}$

A strong-field $d^6$ cobalt(III) complex having the electron configuration $t_{2g}^6\,e_g^0$, 0 unpaired electrons, and an LFSE of $-2.4\Delta_O + 2P$ relative to a spherical-field reference.

Octahedral $d^4$ Spin States

Ligand-field electron configurations where high-spin $d^4$ ($t_{2g}^3\,e_g^1$) contains 4 unpaired electrons and low-spin $d^4$ ($t_{2g}^4\,e_g^0$) contains 2 unpaired electrons.

Permanganate ($\text{MnO}_4^-$)

An oxoanion containing manganese in the $+7$ formal oxidation state with a $d^0$ configuration, whose deep purple color is caused by charge transfer rather than $d\text{–}d$ transitions.

Frost Diagram Disproportionation

A thermodynamic condition indicated when a species lies above the tie-line connecting two surrounding oxidation states, showing that it is thermodynamically unstable toward disproportionation into those states.

Frost Diagram Comproportionation

A thermodynamic condition indicated when an intermediate oxidation state lies below the tie-line connecting two surrounding states, showing that the outer states tend to comproportionate into the intermediate.

Magnetite ($\text{Fe}_3\text{O}_4$)

A mixed-valence iron oxide composed of one Fe(II) and two Fe(III) ions per formula unit, giving an average formal iron oxidation state of $+\frac{8}{3}$.

Deuterium–Tritium Fusion

A nuclear reaction represented by $^2\text{H} + ^3\text{H} \rightarrow ^4\text{He} + ^1n + \text{energy}$, which conserves both mass number ($2 + 3 = 4 + 1$) and nuclear charge ($1 + 1 = 2 + 0$).

Deuterium–Deuterium Fusion Pathway

A nuclear fusion reaction represented by $^2\text{H} + ^2\text{H} \rightarrow ^3\text{He} + ^1n$, in which a neutron ($^1n$) is emitted to conserve mass number and nuclear charge.

Methane Steam Reforming

An industrial hydrogen-producing process represented by $\text{CH}_4 + \text{H}_2\text{O} \rightleftharpoons \text{CO} + 3\text{H}_2$, yielding synthesis gas before the water-gas shift reaction.

Haber Process

The industrial catalytic synthesis of ammonia from nitrogen and hydrogen gases, described by the balanced chemical equation $\text{N}_2 + 3\text{H}_2 \rightleftharpoons 2\text{NH}_3$.

Catalytic Action on Reversible Reactions

The lowering of activation barriers that accelerates the rate of reaching equilibrium in both directions without altering $\Delta G^\circ$, the equilibrium constant $K$, or the equilibrium composition.

Allotropes of Carbon

Structural forms of pure elemental carbon, including diamond, graphite, graphene, fullerenes, and carbon nanotubes.

Graphite Sheet Conduction

Electrical conductivity resulting from three-coordinate carbon atoms with unhybridized $p$ orbitals forming delocalized electronic bands across planar sheets, unlike the wide band gap of tetrahedral diamond.

Zeolite Shape Selectivity

The preferential production of a specific isomer (such as $p$-xylene in modified ZSM-5) due to steric constraints in the microporous network that allow it to diffuse faster than other isomers.

Aluminosilicate Framework Substitution

The replacement of $\text{Si}^{4+}$ with $\text{Al}^{3+}$ in a zeolite framework, which generates one net negative framework charge balanced by an extra-framework cation (such as $\text{Na}^+$ or $\text{H}^+$).

Phosphorus Allotropes

Structural forms of elemental phosphorus, where white phosphorus forms discrete tetrahedral $\text{P}_4$ molecules and common orthorhombic black phosphorus forms extended puckered covalent sheets.

Tetraphosphorus Decaoxide ($\text{P}_4\text{O}_{10}$)

A phosphorus oxide with the empirical formula $\text{P}_2\text{O}_5$ and a phosphorus formal oxidation state of $+5$.

Triplet Ground State of $\text{O}_2$

The $X^3\Sigma_g^-$ ground state of dioxygen, characterized by two unpaired electrons with parallel spins in separate degenerate $\pi^*$ orbitals ($S = 1$, multiplicity $2S + 1 = 3$).

Ozone Catalytic Destruction Cycle

A catalytic atmospheric cycle proceeding via $\text{Cl}^\bullet + \text{O}_3 \rightarrow \text{ClO}^\bullet + \text{O}_2$ and $\text{ClO}^\bullet + \text{O} \rightarrow \text{Cl}^\bullet + \text{O}_2$, yielding the net reaction $\text{O}_3 + \text{O} \rightarrow 2\text{O}_2$.

Oxygen Evolution Half-Reaction

The oxidation of water in acidic solution given by the balanced equation $2\text{H}_2\text{O} \rightarrow \text{O}_2 + 4\text{H}^+ + 4e^-$.

Sulfur Polymorphs

Crystalline allotropes of sulfur, such as orthorhombic and monoclinic sulfur, that both consist of puckered $\text{S}_8$ rings but differ in their solid-state molecular packing.

Face-Centered Cubic (FCC) Lattice

A Bravais lattice adopted by gold under ambient conditions with atoms at the 8 unit cell corners and 6 face centers, containing $8\left(\frac{1}{8}\right) + 6\left(\frac{1}{2}\right) = 4$ atoms per unit cell.

Body-Centered Cubic (BCC) Lattice

A conventional cubic unit cell containing atoms at the 8 corners ($8 \times \frac{1}{8} = 1$) and 1 at the body center, yielding a total of 2 atoms per unit cell.

Translational Symmetry Operations

Crystallographic operations possessing an intrinsic nonzero translation component, specifically including lattice translation, glide reflection, and screw rotation.

Powder X-ray Diffraction (PXRD)

An analytical method using a powder diffractometer that plots diffracted X-ray intensity versus the detector angle $2\theta$ to characterize crystalline phases and interplanar spacings.

Bragg's Law

The fundamental diffraction equation $n\lambda = 2d\sin(\theta)$, relating diffraction order ($n$), X-ray wavelength ($\lambda$), interplanar spacing ($d$), and the Bragg angle ($\theta$).

Square-Planar Coordination

A four-coordinate geometry for an $[\text{ML}_4]$ complex where all four donor atoms are coplanar with the metal, showing adjacent $\text{L}–\text{M}–\text{L}$ angles near $90^\circ$ and opposite angles near $180^\circ$.