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Explain why chlorine (Cl₂) is a gas at room temperature, but sodium chloride (NaCl) is a solid at room temperature - AQA - GCSE Chemistry - Question 2 - 2014 - Paper 1
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Explain why chlorine (Cl₂) is a gas at room temperature, but sodium chloride (NaCl) is a solid at room temperature. Chlorine Cl — Cl Sodium chloride Chloride ion... show full transcript
Worked Solution & Example Answer:Explain why chlorine (Cl₂) is a gas at room temperature, but sodium chloride (NaCl) is a solid at room temperature - AQA - GCSE Chemistry - Question 2 - 2014 - Paper 1
Step 1
Explain why chlorine (Cl₂) is a gas at room temperature
Answer
Chlorine (Cl₂) is a diatomic molecule consisting of two chlorine atoms bonded together by a covalent bond. This type of bond occurs due to the sharing of electrons between the two atoms, resulting in a weak attraction between these small, non-polar molecules. At room temperature, the kinetic energy of these chlorine molecules is sufficient to overcome the weak intermolecular forces, allowing them to exist in a gaseous state. Additionally, chlorine molecules form small, discrete units, so they have a low boiling point, which contributes to their gaseous nature at room temperature.
Step 2
Explain why sodium chloride (NaCl) is a solid at room temperature
Answer
Sodium chloride (NaCl) consists of sodium ions (Na⁺) and chloride ions (Cl⁻) arranged in a three-dimensional crystal lattice structure. The formation of ionic bonds between oppositely charged ions leads to strong electrostatic attractions in all directions throughout the lattice. These ionic bonds require a large amount of energy to break. As a result, sodium chloride has a high melting point and remains solid at room temperature, contrasting with chlorine's gaseous state.
Step 3
Include a description of the bonding and structure of chlorine and sodium chloride
Answer
Chlorine molecules are formed through covalent bonding where two chlorine atoms share electrons, resulting in a simple molecular structure. They are discrete units that exhibit weak Van der Waals forces between them. In contrast, sodium chloride has a robust crystal lattice structure formed by ionic bonds. Each sodium ion is surrounded by six chloride ions, and vice versa, which leads to strong and stable interactions that define its solid state.