To determine which formula represents an ionic compound, let’s analyze each of the given compounds.
1. CH\(_4\) (Methane):
- Methane is composed of one carbon atom and four hydrogen atoms.
- Both carbon and hydrogen are nonmetals.
- The bonds in methane are covalent bonds, where electrons are shared between the carbon and hydrogen atoms.
- Therefore, CH\(_4\) is a covalent compound, not an ionic compound.
2. CuFe (Copper-Iron Alloy):
- This formula suggests a mixture of copper (Cu) and iron (Fe).
- Alloys are typically mixtures of two or more elements, usually metals.
- In this case, CuFe is a metallic alloy, where metallic bonding is predominant.
- Thus, CuFe is not an ionic compound, but rather a metallic compound.
3. AlCl\(_3\) (Aluminum Chloride):
- Aluminum chloride consists of one aluminum atom and three chlorine atoms.
- Aluminum (Al) is a metal and chlorine (Cl) is a nonmetal.
- Aluminum can lose three electrons to form an Al\(^{3+}\) ion, and each chlorine atom can gain one electron to form three Cl\(^{-}\) ions.
- The electrostatic attraction between Al\(^{3+}\) and Cl\(^{-}\) ions forms an ionic bond.
- Therefore, AlCl\(_3\) is an ionic compound.
Given the analysis, among the provided compounds, AlCl\(_3\) (Aluminum Chloride) is the one that represents an ionic compound. Thus, the correct answer is:
[tex]\[
\boxed{AlCl_3}
\][/tex]
This corresponds to index 2 when considering the given list: "CH4", "CuFe", "AlCl3".
