To understand why sodium chloride (NaCl) is an ionic compound while hydrogen chloride (HCl) is a gas, we need to analyze the nature of the bonds formed in each compound and the properties associated with those bonds.
### Step-by-Step Solution:
1. **Identify the Components of Each Compound:**
- Sodium chloride (NaCl) consists of sodium ions (Na⁺) and chloride ions (Cl⁻).
- Hydrogen chloride (HCl) consists of hydrogen (H) and chlorine (Cl).
**Hint:** Look at the elements involved in each compound and their positions in the periodic table.
2. **Determine the Types of Elements:**
- Sodium (Na) is a metal, and chlorine (Cl) is a non-metal.
- Both hydrogen (H) and chlorine (Cl) are non-metals.
**Hint:** Recall that metals typically form cations, while non-metals form anions.
3. **Analyze the Bonding:**
- In NaCl, the bond formed between Na and Cl is ionic. This occurs because sodium donates an electron to chlorine, resulting in the formation of Na⁺ and Cl⁻ ions, which are held together by strong electrostatic forces.
- In HCl, the bond formed is covalent. Both hydrogen and chlorine share electrons rather than transferring them, resulting in a covalent bond.
**Hint:** Remember that ionic bonds are formed through electron transfer, while covalent bonds involve electron sharing.
4. **Evaluate the Strength of the Bonds:**
- Ionic bonds are generally stronger than covalent bonds due to the strong electrostatic attraction between oppositely charged ions.
- Covalent bonds, like those in HCl, are weaker and have lower melting and boiling points.
**Hint:** Consider how bond strength affects the physical state of a substance at room temperature.
5. **Consider Physical Properties:**
- Sodium chloride is a solid at room temperature, with a high melting point due to the strong ionic bonds.
- Hydrogen chloride, being a covalent compound, is a gas at room temperature, with low melting and boiling points.
**Hint:** Think about how bond type influences the state of matter (solid, liquid, gas) at room temperature.
### Conclusion:
Sodium chloride is an ionic compound due to the presence of strong ionic bonds formed between a metal and a non-metal, resulting in a solid state. In contrast, hydrogen chloride is a gas because it consists of covalent bonds between non-metals, which are weaker and result in lower melting and boiling points.
