Which arrangement of cations (yellow) and anions (blue) in a lattice is the more stable? Explain your reasoning. (a)



(b)

Verified step by step guidance

1. Identify the arrangement of cations (yellow) and anions (blue) in both lattice structures I and II.
2. Recall that lattice stability is influenced by the electrostatic attraction between oppositely charged ions and the repulsion between like-charged ions.
3. Observe that in arrangement I, the central cation is surrounded by six anions, maximizing the electrostatic attraction and minimizing repulsion.
4. In arrangement II, the central cation is surrounded by fewer anions, leading to less electrostatic attraction and potentially more repulsion between like-charged ions.
5. Conclude that arrangement I is more stable due to the higher coordination number, which enhances the electrostatic attraction and overall stability of the lattice.

Key Concepts

Ionic Bonding

Ionic bonding occurs when cations and anions attract each other due to their opposite charges. This electrostatic attraction leads to the formation of a stable ionic lattice structure, where the arrangement of ions minimizes potential energy. The stability of the lattice is influenced by the size and charge of the ions involved.

Lattice Energy

Lattice energy is the energy released when gaseous ions combine to form an ionic solid. It is a measure of the strength of the forces between the ions in the lattice. A higher lattice energy indicates a more stable arrangement, as it reflects stronger attractions between the cations and anions, which can be influenced by their charges and distances apart.

Coordination Number

The coordination number refers to the number of nearest neighbors surrounding a central ion in a lattice structure. It plays a crucial role in determining the stability of the lattice; higher coordination numbers typically lead to greater stability due to increased ionic interactions. The arrangement of ions in the lattice affects the coordination number and, consequently, the overall stability.