CHEM2077: Group 14 Elements Flashcards

Vocabulary flashcards covering the physical properties, periodic trends, bonding characteristics, and various compounds (hydrides, halides, and carbides) of Group 14 elements.

Group 14 Valence Electron Configuration

The elements in this group possess an $ns^2\,np^2$ valence electron configuration.

Inert Pair Effect

The trend in Group 14 where the $+2$ oxidation state becomes increasingly stable relative to the $+4$ state as you descend the group.

Catenation

The ability of an element to form long chains and rings; Carbon is unique in this ability due to the high strength of the $C-C$ bond ($348\,kJ\,mol^{-1}$).

$Si-Si$ Bond Strength

$$226\,kJ\,mol^{-1}$$

$Ge-Ge$ Bond Strength

$$188\,kJ\,mol^{-1}$$

$Sn-Sn$ Bond Strength

$$151\,kJ\,mol^{-1}$$

Group 14 Hydrides ($EH_4$) Thermal Stability

Stability decreases down the group; $CH_4$ is very stable while $PbH_4$ is barely known due to decreasing orbital overlap effectiveness.

Silicon Tetrahalide Hydrolysis

Si halides are susceptible to hydrolysis because the availability of empty $3d$ orbitals on Si allows for nucleophilic attack by water.

$PbCl_4$ Stability

This halide is unstable and decomposes to $PbCl_2$ and $Cl_2$, reflecting the stability of the $+2$ state in Lead.

$3p-3p$ $\pi$-overlap

A mechanism that is much less effective than $2p-2p$ $\pi$-overlap, explaining why Silicon does not readily form multiple bonds ($Si=Si$ or $Si=O$).

Silica ($SiO_2$)

A compound that forms vast network structures of single bonds rather than discrete molecules like $CO_2$.

Steric Protection

The use of bulky substituent groups to synthesize heavier Group 14 multiple bonds ($M=M$) and prevent polymerization into single-bonded species.

Saline Carbides

Carbides formed by Group 1 and 2 metals (e.g., $CaC_2$) containing $C_2^{2-}$ ions that react with water to produce ethyne.

Interstitial Carbides

Carbides formed by transition metals (e.g., $WC$) where Carbon atoms occupy holes in the metal lattice, resulting in very hard, high-melting-point materials.

Covalent Carbides

Carbides such as Silicon Carbide ($SiC$), also known as "Carborundum," which feature a diamond-like structure and extreme hardness.