Photo AI
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
Question 2
Explain why chlorine (Cl₂) is a gas at room temperature, but sodium chloride (NaCl) is a solid at room temperature. Include a description of the bonding and structu... 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 composed of two chlorine atoms bonded together by a covalent bond. The forces between these individual Cl₂ molecules are relatively weak van der Waals forces. At room temperature, these weak intermolecular forces are insufficient to hold the molecules in a solid or liquid state, allowing chlorine to exist as a gas. Moreover, the low boiling point of chlorine, which is around -34 °C, further supports its gaseous state at room temperature.
Step 2
Explain why sodium chloride (NaCl) is a solid at room temperature
Answer
Sodium chloride (NaCl) is an ionic compound formed from the electrostatic attraction between sodium ions (Na⁺) and chloride ions (Cl⁻). In NaCl, strong ionic bonds result from the transfer of electrons from sodium to chlorine, creating a strong attraction that holds the oppositely charged ions together. This ionic lattice structure requires a significant amount of energy to break the bonds, leading sodium chloride to be stable and solid at room temperature. The high melting point of NaCl, approximately 801 °C, confirms its solid state under these conditions.
Step 3
Describe the bonding and structure of chlorine
Answer
Chlorine exists as Cl₂ molecules, which are held together by covalent bonds. Each chlorine atom shares one electron with another chlorine atom, forming a diatomic molecule. The Cl₂ molecule is nonpolar due to the equal electronegativity of the two chlorine atoms, allowing it to exist as a gas at room temperature. The molecules are free to move independently, contributing to chlorine's gaseous state.
Step 4
Describe the bonding and structure of sodium chloride
Answer
Sodium chloride is structured in a crystal lattice, where each sodium ion is surrounded by six chloride ions and vice versa. The ionic bonds in this lattice are formed through the transfer of electrons, where sodium loses one electron to become Na⁺ and chlorine gains that electron to become Cl⁻. This arrangement maximizes stability and minimizes repulsion between the ions, making NaCl a solid with a high melting point.