Question

Which of the following statements is correct in the body centered type cubic structure of an ionic compound? (a) Co-ordination number of each cation and anion is two (b) Co-ordination number of each cation and anion is four (c) Co-ordination number of each cation and anion is six (d) Co-ordination number of each cation and anion is eight

Short answer

The correct statement for the body centered cubic structure of an ionic compound is (d) Co-ordination number of each cation and anion is eight.

Step-by-step solution

Understanding Coordination Number

The coordination number is the number of atoms that immediately surround a central atom in a crystal lattice. In a body-centered cubic (bcc) structure, the central atom is surrounded by eight other atoms: one at each corner of the cube.

Analyzing Body Centered Cubic Structure

In a body centered cubic (bcc) structure, the central atom has one atom at the center of the cube and another eight atoms at the corners of the cube. Since the corner atoms are shared among eight adjacent cells, each contributes 1/8 of an atom to the cell containing the central atom.

Determining the Correct Answer

Based on the body centered cubic structure characteristics, each cation and anion in such a lattice will have a coordination number of eight, as they are each surrounded by eight other atoms. This is true for both the cation in the center and the anions at the corners of the cube, or vice versa.

Key concepts

Coordination Number in Ionic Compounds

By exploring the coordination number, we delve into the fascinating world of crystal structures and atomic arrangements. The coordination number is a fundamental concept in understanding the stability and properties of solid materials, especially in the realm of ionic compounds. It refers to the number of nearest neighbors or atoms that surround a given atom within a crystal. For instance, consider a huge crowd in a room where one person is surrounded by others; the number of people closest to that individual is analogous to an atom's coordination number in the context of a crystal.

Within a body-centered cubic (bcc) structure, a central atom is positioned at the very heart of a cube, with other atoms snugly occupying the corners. These corner atoms are akin to guests sharing standing-room space at the corners of the room, each imparting a fractional presence to the central position. After adjusting for the shared contributions, we find that the central atom boasts a coordination number of eight, signifying that it is embraced by eight other atoms. This holds true for every atom residing at the heart of its own microscopic cubic 'room', indicating the stability and uniformity within such structures. When learning chemistry, picturing this three-dimensional arrangement can significantly enhance your grasp of material behavior.

The Body-Centered Cubic Crystal Lattice

The crystal lattice is essentially the scaffolding of a crystalline solid, with perfectly ordered atoms creating an immense network stretching in all three dimensions. The beauty of a body-centered cubic lattice lies in its simplicity and efficiency; imagine a stack of equally sized cubes, and within each cube, an item is positioned at every corner and one right at the center. This pattern repeats itself, extending into a masterful, continuous three-dimensional grid.

Think of building blocks where each box is meticulously placed in alignment with others to maintain a particular structure; this is how atoms align in a crystal lattice. But every lattice has its unique characteristics. For a body-centered cubic (bcc) structure specifically, we are concerned with the positioning of eight atoms that define the corners of the cube and one additional atom resting peacefully in the center. These arrangements dictate not only the physical strength and density of metals and alloys but also influence their melting points, conductivity, and other crucial properties. Understanding the crystal lattice of an element or compound allows material scientists and engineers to predict and manipulate these properties for various applications. As a student, visualizing this geometric pattern can offer profound insights into how materials operate at the most basic level.

Ionic Compounds and Their Structures

When we consider ionic compounds, we step into a realm where charged entities, ions, come together in an orchestrated dance governed by electrostatic forces—the attraction between positively charged cations and negatively charged anions. The structure of these compounds is not haphazard but instead follows strict geometric principles that ensure overall neutrality and stability of the lattice. This attraction and organization lead to the formation of solid compounds with high melting points and electrical conductivity when molten.

Every ionic compound has its characteristic crystal lattice that decides its physical properties. For instance, table salt, sodium chloride (NaCl), forms a cubic crystal lattice, where each sodium ion is flanked by six chloride ions and vice versa, resulting in a coordination number of six. On the other hand, as we've discussed, a body-centered cubic system has a different structure, with atoms connecting to eight others. The subtle yet profound differences in these lattices are central to the diversity of ionic compounds and their uses in various industries. As you embark on experiments or solve problems related to ionic compounds, keep in mind their crystal lattices, and envision the arrangement of ions for a better conceptual understanding.