Question

Solid NaCl is a bad conductor of electricity because (1) In solid \(\mathrm{NaCl}\), there are no ions. (2) Solid NaCl is covalent. (3) In solid \(\mathrm{NaCl}\), there is no movement of ions. (4) In solid \(\mathrm{NaCl}\), there are no electrons.

Short answer

Option (3).

Step-by-step solution

- Understand the nature of NaCl

NaCl, or sodium chloride, is an ionic compound. This means it is composed of positively and negatively charged ions.

- Consider the state of NaCl

In the solid state, the ions in NaCl are held rigidly in a lattice structure. This implies that the ions cannot move freely.

- Analyze why solid NaCl is a bad conductor

For electrical conduction to occur, charged particles (ions or electrons) need to move. In solid NaCl, the ions are fixed in place and cannot move, which prevents the conduction of electricity.

- Evaluate the given options

The correct statement is (3) In solid \(\text{NaCl}\), there is no movement of ions. This is because the fixed position of ions in the lattice structure of solid NaCl prevents electrical conduction.

Key concepts

ionic compounds

Ionic compounds are formed when atoms transfer electrons to each other. This transfer creates ions: positively charged cations and negatively charged anions. The opposite charges attract, creating a strong ionic bond that holds the compound together.

• Example: NaCl (sodium chloride) is made from sodium (Na) transferring an electron to chlorine (Cl).
• The result is Na⁺ (sodium ion) and Cl^- (chloride ion).

These ions are arranged in a regular pattern, forming a crystal lattice structure. It's important to remember that while ionic compounds can conduct electricity when molten or dissolved in water, they generally cannot do so in their solid form.

lattice structure

The lattice structure in ionic compounds, like solid NaCl, is a highly ordered and rigid arrangement of ions. This structure maximizes the attraction between oppositely charged ions and minimizes repulsion between similarly charged ions.

• A lattice can be thought of as a 3D grid where each ion is surrounded by ions of the opposite charge.
• For NaCl, each sodium ion (Na⁺) is surrounded by six chloride ions (Cl^-), and vice-versa.

This rigid and fixed arrangement is key to understanding why solid ionic compounds do not conduct electricity.

electrical conduction

Electrical conduction involves the movement of charged particles. In ionic compounds, this movement can be of ions or electrons. To conduct electricity, these charged particles must be free to move.

• In solid NaCl, the ions are fixed in place within the lattice structure and cannot move freely. Therefore, solid NaCl cannot conduct electricity.
• When NaCl is melted, the ions are free to move, allowing the substance to conduct electricity.
• Similarly, when NaCl is dissolved in water, the ions dissociate and are free to move, also allowing for electrical conduction.

It’s the movement of these charged particles that enables the flow of current, making it crucial to understand the state of the ionic compound when discussing electrical conduction.