Main-Group and Solid-State Chemistry -- Practice Problems
Main-Group and Solid-State Chemistry — Practice Problems
10 MCQ questions covering main-group element trends, Bravais lattices, crystal structures, defects, and electronic properties of solids. Select an option to check your answer.
Main-Group Chemistry
Solid-State Chemistry
Intuition
Main group chemistry follows predictable periodic trends: Elements in groups 1-2 and 13-18 behave in systematic ways based on their valence electrons. Solid-state chemistry extends this to crystal structures, band theory, and the properties of materials like semiconductors and superconductors.
Why it matters: Solid-state chemistry drives modern technology, silicon chips, LED displays, lithium-ion batteries, and solar cells all depend on understanding how atoms pack into crystals and how electrons move through solids.
The key insight: Band theory explains the spectrum from insulators to conductors, the size of the band gap between valence and conduction bands determines whether a material conducts electricity.
Common Mistakes
Confusing metals, semiconductors, and insulators by band gap alone: The band gap determines conductivity at a given temperature. A 6 eV gap means insulator at room temperature, but at very high temperatures, even insulators can conduct. Context matters, a material’s classification depends on conditions, not just the band gap value.
Assuming all ionic compounds are soluble: Solubility depends on lattice energy vs hydration energy. Many ionic compounds are insoluble (e.g., BaSO₄, AgCl). The solubility rules (like “nitrates are soluble”) are useful guidelines but not absolute, always check specific data rather than relying solely on general rules.
Confusing coordination number with oxidation state: Coordination number is the number of ligand donor atoms directly bonded to the metal (e.g., 6 in [Co(NH₃)₆]³⁺). Oxidation state is the charge on the metal after assigning ligand charges. A metal can have coordination number 6 with oxidation state +2 or +3 or other values. These are independent properties.