Question

Which of the following structure is similar to graphite? (1) $\mathrm{B}$ (2) ${\overline{B}}_{4}C$ (3) ${\mathrm{B}}_2{\mathrm{H}}_6$ (4) $\mathrm{BN}$

Short answer

Option (4) $\mathrm{BN}$

Step-by-step solution

Identify Structural Characteristics of Graphite

Graphite is composed of layers of carbon atoms arranged in a hexagonal lattice. Identify structures in the options that have similar characteristics such as planar layers or hexagonal arrangements.

Analyze Option (1) $\mathrm{B}$

Boron ($\mathrm{B}$) does not possess a layered hexagonal structure similar to graphite. Therefore, option (1) is not similar to graphite.

Analyze Option (2) ${\overline{B}}_{4}C$

${\overline{B}}_{4}C$ does not have a planar hexagonal structure. Thus, option (2) cannot be similar to graphite.

Analyze Option (3) ${\mathrm{B}}_2{\mathrm{H}}_6$

Diborane (${\mathrm{B}}_2{\mathrm{H}}_6$) is a molecular compound and does not have a hexagonal planar layer structure like graphite. Therefore, option (3) is not similar to graphite.

Analyze Option (4) $\mathrm{BN}$

Hexagonal boron nitride ($\mathrm{BN}$) has a structure similar to graphite, with hexagonal layers and similar planar arrangements.

Conclusion

After analyzing all the options, $\mathrm{BN}$ (option 4) is the structure similar to graphite due to its hexagonal layered structure.

Key concepts

hexagonal lattice

A hexagonal lattice is a repeating pattern where atoms are arranged in hexagons. This structure is crucial in understanding materials like graphite and hexagonal boron nitride.
Both of these materials consist of planar sheets of atoms interconnected in hexagon shapes.
Think of it as a honeycomb-like pattern but on the atomic scale. These hexagons fit together perfectly, creating a continuous two-dimensional layer.
The unique arrangement ensures stability and specific electronic properties.
Moreover, the layers stick to one another using weak forces called van der Waals forces.
This feature allows the layers to slide over each other easily, offering unique properties such as lubricity in graphite.

boron nitride

Boron nitride (BN) is an interesting compound that can take various forms, but in this context, we focus on hexagonal boron nitride.
This form of BN closely resembles the structure of graphite.
Just like graphite, hexagonal boron nitride is made up of layers of atoms arranged in a hexagonal pattern, creating planar sheets.
One key difference, however, is in the elements; while graphite consists of only carbon atoms, hexagonal boron nitride has alternating boron (B) and nitrogen (N) atoms.
This alternating pattern still maintains the hexagonal structure, but it slightly changes the material's properties. For instance,

• Hexagonal BN is an excellent electrical insulator.
• It has superb thermal conductivity, making it useful in high-temperature applications.

Understanding this similarity helps in recognizing why BN, among other given options, is structurally similar to graphite.

planar layers

Planar layers refer to flat, two-dimensional sheets of atoms that stack on top of each other.
These are crucial in materials like graphite and hexagonal boron nitride.
Each planar layer in these materials holds atoms arranged in a hexagonal lattice.
In graphite, each layer is solely composed of carbon atoms forming a hexagonal pattern. Similar layers in hexagonal boron nitride consist of alternating boron and nitrogen atoms.
The weak van der Waals forces between these layers allow them to slide over one another. This sliding capability gives graphite its slippery feel, making it an excellent lubricant.
Additionally, the planar nature contributes to the materials' electrical and thermal properties.

• In graphite, these layers make it a good conductor of electricity.
• In hexagonal boron nitride, they create high thermal conductivity but electrical insulation.

So, when discussing planar layers, it's essential to consider how these flat structures influence the material's functionality.