Overview
This lecture reviews common chemical substances, including their structures, chemical formulas, and key properties, with examples from molecules, compounds, allotropes, metals, and mixtures.
Simple Molecules
- Water (H₂O) has a bent structure, is polar, liquid at room temperature, and dissolves many substances.
- Carbon dioxide (CO₂) is a linear molecule, gaseous at room temperature, acidic in water, and used for carbonation.
- Oxygen (O₂) is a diatomic molecule, gaseous at room temperature, supports combustion, and is vital for respiration.
Compounds with Clear Properties
- Sodium chloride (NaCl) forms a cubic crystal lattice, is solid, dissolves in water, and conducts electricity when dissolved.
- Glucose (C₆H₁₂O₆) has a ring structure, is a crystalline solid, dissolves in water, and tastes sweet.
- Quartz (SiO₂) has a 3D network structure, is hard, insoluble in water, and used in glass making.
Allotropes of Carbon
- Diamond (C) features a 3D tetrahedral lattice, is extremely hard, non-conductive, and transparent.
- Graphite (C) consists of layered hexagonal sheets, is soft, conducts electricity, and used in pencils.
- Fullerene (C₆₀) is a spherical molecule, stable, and has potential electronic applications.
Metals
- Copper (Cu) is a reddish, malleable metal, conducts heat and electricity, and forms a metallic lattice.
- Aluminum (Al) is lightweight, corrosion-resistant, used in cans and airplanes, and has a metallic lattice.
- Iron (Fe) is strong, magnetic, rusts when exposed to water and oxygen, and forms a metallic lattice.
Mixtures
- Air is a mixture of nitrogen, oxygen, and carbon dioxide with no chemical bonding and supports life/combustion.
- Saltwater is a mixture of NaCl dissolved in H₂O with dispersed ions, tastes salty, and conducts electricity.
- Granite is a mixture of minerals like quartz, feldspar, and mica, is hard, and used in construction.
Key Terms & Definitions
- Molecule — two or more atoms bonded together, can be simple (e.g., O₂) or complex (e.g., C₆H₁₂O₆).
- Compound — substance formed when two or more elements are chemically bonded (e.g., NaCl).
- Allotrope — different structural forms of the same element (e.g., diamond, graphite, fullerene for carbon).
- Metallic lattice — arrangement of metal atoms in a solid metal, allowing electrical conductivity.
- Mixture — combination of substances not chemically bonded, can be separated physically.
Action Items / Next Steps
- Review and memorize the properties and structures of each listed substance.
- Prepare substance cards for each example to reinforce learning.
- Complete any assigned homework on identifying substances and mixtures.