Types of Compounds & Properties
Core Concept
Compounds are classified based on the types of bonds that hold their atoms together and their resulting structures. Understanding the different types of compounds—such as ionic, covalent, metallic, and network covalent compounds—helps us predict their physical and chemical properties, like melting and boiling points, conductivity, and solubility. Each type of compound has unique characteristics that arise from the nature of the interactions between its constituent particles.
Confusing conductivity conditions - Ionic compounds only conduct when ions are mobile
Ignoring electronegativity differences - Always calculate ΔEN to predict bonding
Overgeneralizing solubility - Learn the specific solubility rule exceptions
Mixing up covalent types - Molecular vs network have very different properties
Test Yourself
Podcast Episode
Practice Problems & Worked Out Examples 🔒
Browse by category
Classification Based on Constituent Elements/Chemical Formula
→ 02Prediction of Physical Properties Based on Compound Type
→ 03Explanation of Structure-Property Relationship
→ 04Identification of Compound Type from Experimental Data/Property Descriptions
→ 05Evaluation and Error Analysis of Property Data
→ 06Other / Uncategorized
→ 07Assorted Multiple Choice
→Core Concept - Property Comparison
| Property | Ionic | Molecular Covalent | Network Covalent | Metallic |
|---|---|---|---|---|
| Melting Point | High | Low | Very High | Variable |
| Electrical Conductivity | Only when molten/dissolved | Poor | Variable | Excellent |
| Solubility in Water | Often soluble | Variable ("like dissolves like") | Usually insoluble | Insoluble |
| Mechanical Properties | Brittle | Soft, flexible | Very hard | Malleable, ductile |
| Examples | NaCl, MgO | H₂O, CH₄ | Diamond, SiO₂ | Cu, steel |
$\boxed{\text{EXAMPLE PROBLEM}}$
Predict the bonding type and properties of MgO
Hint: Calculate electronegativity difference, determine bonding type, list expected properties
MgO: ΔEN = 2.3 (ionic) → High melting point, brittle, conducts when molten, soluble in water
$\boxed{\text{EXAMPLE PROBLEM}}$
Explain why diamond has a high melting point but methane (CH₄) has a low melting point.
Diamond vs CH₄: Diamond has network covalent bonds throughout (break covalent bonds to melt), CH₄ only has weak intermolecular forces between molecules
View more practice problems here.
Laboratory Identification Methods
Electrical Conductivity Test
Solid ionic: No conductivity
Molten/dissolved ionic: Conducts
Molecular covalent: No conductivity
Metallic: Excellent conductivity
Solubility Test
Polar solvents (water): Dissolves ionic and polar covalent
Nonpolar solvents: Dissolves nonpolar covalent
"Like dissolves like" rule
Melting Point Determination
High (>800°C): Ionic or network covalent
Low (<400°C): Molecular covalent
Variable: Metallic
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