Solid State Chemistry Lecture 1 Practice Flashcards

Comprehensive practice questions covering types of solids, bonding models (covalent, ionic, metallic, van der Waals), thermal characterization (TGA, DSC), and periodic trends (Ionization Energy, Electron Affinity).

How does the density of a solid generally compare to that of its liquid and gas phases?

The density of a solid and a liquid of the same material are roughly the same (within a factor of $10$), whereas the density of a gas is approximately $1000 \times$ smaller.

What characterizes a crystalline solid in terms of molecular arrangement?

A crystalline solid has long range order, defined as having more than $10^3$ molecules or atoms in any one direction.

What is the definition of a 'glass' in the context of solid types?

Glasses are a special case of noncrystalline/amorphous solids that possess short range order but no long range ordering.

What are the typical properties of covalent solids?

Covalent solids are characteristically rigid, electrically insulating (usually), and have high melting points.

According to the transcript, what is the formula for the electrostatic (Coulombic) force ($F$) between two ions?

F = - \frac{Z_1 Z_2}{4 \text{\pi} \text{\epsilon}_0 r^2}, where $Z_1$ and $Z_2$ are ionic charges, \text{\epsilon}_0 is the permittivity of free space, and $r$ is the separation.

What is the formula used to calculate the internal energy ($U$) change for two ions moved from infinity to a separation $r$?

U = \frac{Z_1 Z_2}{4 \text{\pi} \text{\epsilon}_0 r}

Why are ionic solids considered brittle?

Displacing ions by one spot aligns ions of like polarity (e.g., cation next to cation), creating a highly repulsive force that causes the crystal to crack along cleavage planes.

What type of bonding allows for delocalised sharing where atoms donate electrons into a 'sea' of electrons?

Metallic bonding.

What is the solubility formula for an ionic solid dissolving in water?

\text{\Delta} H_{\text{soln}} = -\text{\Delta} H_{\text{lattice}} + \text{\Delta} H_{\text{solution}}

Which thermal characterization technique is used to determine the stoichiometric amounts of volatile components, such as water of crystallisation?

Thermogravimetric analysis (TGA).

In Differential Scanning Calorimetry (DSC), how are exothermic and endothermic phase changes identified on a plot of power vs. time?

A peak represents an exothermic reaction (\text{\Delta} H negative), and a trough represents an endothermic reaction (\text{\Delta} H positive).

What is the definition of the First Ionisation Energy ($I_e$)?

The change in internal energy at $0 \text{\,} K$ for the process $M_{(g)} \rightarrow M^+_{(g)} + e^-$, where one mole of gaseous atoms becomes one mole of gaseous monopositive ions.

Why do larger atoms have lower ionisation potentials?

Outer electrons are further from the nucleus and better shielded by inner electrons, making them easier to remove.

What is unique about the thermodynamic sign convention for First Electron Affinity ($E_a$)?

Unlike other quantities, a positive value for $E_a$ represents an exothermic process (heat leaving the system) for the attachment of an electron to a gaseous atom.

According to the lecture, why are anions generally larger than cations?

Cations have a positive charge that pulls electrons inward, while the negative charge of anions allows electrons to move outwards.

What are the coordination numbers for $NaCl$ and $CaF_2$ mentioned in the notes?

$NaCl$ has $6:6$ coordination and $CaF_2$ has $8:4$ coordination.

What was the cause of the Comet 1 jet airplane crashes mentioned in the lecture?

Metal fatigue, which involved the formation of microscopic cracks by cyclic loading and unloading of the metal body.