Molecular Substances and Carbon Chemistry Notes

Molecular Substances

• Molecules are small particles made of atoms.
• Smallest molecule: Hydrogen (H₂).
• Largest molecule: DNA (millions of atoms).
• Molecules are discrete with defined shapes.
• Molecular substance: Made of molecules, different properties from metals/ionic substances.
• Chemical formula: Type and number of atoms in a molecule.

Introduction to Carbon

• Organic chemistry: Study of carbon chemistry.
• Molecules are made of 92 kinds of atoms (Periodic Table).
• Example: Carbon dioxide (CO₂) has 1 carbon and 2 oxygen atoms.

Molecule Classification

• Diatomic: Two atoms (e.g., Nitrogen (N₂), Chlorine (Cl₂)).
• Polyatomic: More than two atoms (e.g., Carbon dioxide (CO₂), Propane (C₂H₈), Sulfur (S₈)).
• Macromolecules: Many hundreds of atoms (e.g., DNA, Diamond).

Key Definitions

• Organic chemistry: Chemistry concerned with carbon compounds.
• Molecule: Discrete particle, atoms covalently bonded.

Atoms in Molecules

• H₂O: 3 atoms (Hydrogen, Oxygen)
• N₂: 2 atoms (Nitrogen)
• Cl₂: 2 atoms (Chlorine)
• CH₄: 5 atoms (Carbon, Hydrogen)
• C₃H₆: 9 atoms (Carbon, Hydrogen)

Carbon Atom

• Carbon (C): Atomic number 6 (6 protons, 6 electrons).
• Electron configuration: 2,4 (4 valence electrons).
• Neutrons: Atomic mass - Atomic number (12 - 6 = 6).
• Valence shell: Outermost electron shell.
• Carbon needs to gain 4 electrons for a full valence shell.