Chemical Bonding Overview

Study Notes

Chemical Bonding

Chemical bonding governs compound formation and atomic interactions.
It's the force holding atoms together, creating stable molecules and materials.

Types of Chemical Bonds

Ionic Bonds:
- Formed between a metal and a nonmetal.
- Involve complete electron transfer from metal to nonmetal.
- Create positively and negatively charged ions (cations and anions).
- High melting and boiling points, high lattice energies.
- Examples: NaCl (table salt), CaCl₂ (calcium chloride)
Covalent Bonds:
- Formed between two nonmetals.
- Involve electron sharing between atoms.
- Create stable, neutral molecules.
- Low melting and boiling points, relatively low bond energies.
- Examples: H₂O (water), CH₄ (methane)
Metallic Bonds:
- Formed between metal atoms.
- Involve delocalized valence electrons (a "sea of electrons").
- Result in solid, malleable, conductive materials.
- High melting and boiling points, high thermal and electrical conductivity.
- Examples: Cu (copper), Al (aluminum)
Hydrogen Bonds:
- A special dipole-dipole interaction.
- Formed between a hydrogen atom bonded to a highly electronegative atom (N, O, F) and another highly electronegative atom.
- Relatively weak, but can significantly influence molecular properties.
- Examples: H₂O (water), NH₃ (ammonia)

Factors Influencing Bond Formation

Electronegativity Difference:
- Measures atoms' ability to attract shared electrons.
- Determines bond's ionic or covalent character.
- Higher differences result in more ionic character.
Atomic Size:
- Larger atoms form weaker bonds due to increased distance.
- Smaller atoms form stronger bonds due to proximity.
Octet Rule:
- Atoms tend to bond to achieve a stable 8 valence electron configuration.
- Exceptions include H (2 electrons) and He (0 electrons).
Bond Polarity:
- Unequal electron sharing in covalent bonds.
- Creates partial positive and negative charges (dipoles).
- Influences molecular properties and reactivity.

Chemical Reactions

Synthesis (Combination) Reactions:
- Two or more reactants combine to form a single product.
- General formula: A + B → AB.
- Example: 2Na + Cl₂ → 2NaCl
Decomposition Reactions:
- A single reactant breaks down into two or more products.
- General formula: AB → A + B.
- Example: 2H₂O → 2H₂ + O₂
Single Displacement (Substitution) Reactions:
- One element replaces another in a compound.
- General formula: A + BC → AC + B.
- Example: 2Na + 2HCl → 2NaCl + H₂
Double Displacement (Metathesis) Reactions:
- Two compounds exchange ions to form two new compounds.
- General formula: AB + CD → AD + CB.
- Example: NaCl + AgNO₃ → NaNO₃ + AgCl
Acid-Base Reactions:
- Involve proton (H⁺) transfer between an acid and a base.
- General formula: HA + BOH → A⁻ + B⁺ + H₂O.
- Example: HCl + NaOH → Cl⁻ + Na⁺ + H₂O
Redox (Oxidation-Reduction) Reactions:
- Involve electron transfer between reactants.
- Oxidation: Loss of electrons.
- Reduction: Gain of electrons.
- General example (oxidation): A → A⁺ + e⁻
- General example (reduction): B + e⁻ → B⁻
- Example: 2Na + 2HCl → 2NaCl + H₂ (Na is oxidized, H is reduced)

Description

Explore the fundamentals of chemical bonding, including ionic, covalent, and metallic bonds. Understand how these bonds govern the formation of compounds and atomic interactions. Test your knowledge of the types of bonds and their properties.