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| Property | Ionic Bond ⚡ | Covalent Bond 🔗 | Metallic Bond 🧲 |
|---|---|---|---|
| Elements involved | Metal + Nonmetal | Nonmetal + Nonmetal | Metals only |
| Electron behavior | Transferred (lost/gained) | Shared | Delocalized (“sea” of e⁻) |
| Structure | Crystal lattice | Molecules or networks | Metal lattice |
| Melting point | High | Low–medium (very high in networks) | Usually high |
| Electrical conductivity | High when molten or dissolved | Poor | High (solid state) |
| Solubility in water | Often soluble | Usually low | Insoluble |
| Physical state | Solid (at room temp) | Solid/liquid/gas | Solid (except Hg) |
| Examples | NaCl, MgO | H₂O, CO₂, CH₄ | Fe, Cu, Al |
Chemical Bonding
Chemical bonding is the force that holds atoms together in compounds, creating the incredible diversity of materials around us. From the salt in our food to the water we drink, from the metals in our buildings to the DNA in our cells, everything depends on how atoms bond together.
Ionic Bonding
Formed between metals and non-metals through electron transfer, creating charged ions that attract each other. Metals lose electrons to become positively charged cations, while non-metals gain electrons to become negatively charged anions.
Physical Properties
- Crystal structure: Regular, repeating arrangement of ions
- High melting/boiling points: Strong electrostatic attractions
- Brittle: Shifting layers brings like charges together, causing repulsion
- Hard: Strong ionic bonds resist deformation
Electrical Properties
- Insulators when solid: Ions are fixed in the lattice
- Conduct when molten: Ions are free to move
- Conduct when dissolved: Ions dissociate in solution
- Electrolytes: Aqueous solutions conduct electricity
Solubility
- Polar solvents: Often soluble in water
- Hydration: Water molecules surround and stabilize ions
- Non-polar solvents: Usually insoluble
- Lattice energy: Influences solubility
Covalent Bonding
Formed between non-metals through electron sharing. Atoms share pairs of electrons to achieve a stable electron configuration (often following the octet rule), forming molecules.
Physical Properties
- Low to moderate melting/boiling points: Weak intermolecular forces (except network solids)
- States: Can be gases, liquids, or soft solids
- Not brittle: Many are flexible or soft
- Exceptions: Giant covalent structures (e.g., diamond) are very hard
Electrical Properties
- Poor conductors: No free charged particles
- Exceptions: Graphite conducts due to delocalized electrons
Solubility
- Polar molecules: May dissolve in water
- Non-polar molecules: Dissolve in non-polar solvents
- "Like dissolves like": Solubility depends on polarity
Types of Bonds
- Single bond: One shared pair of electrons
- Double bond: Two shared pairs of electrons
- Triple bond: Three shared pairs of electrons
Metallic Bonding
Formed between metal atoms, where valence electrons become delocalized, creating a "sea of electrons" surrounding positively charged metal ions.
Properties from Metallic Bonding
Electrical Conductivity
- Mobile electrons: Carry electric current
- Excellent conductors: e.g., silver, copper, gold
- Temperature effect: Conductivity decreases with increasing temperature
- Non-directional: Conduct in all directions
Thermal Conductivity
- Heat transfer: Mobile electrons carry thermal energy
- Good thermal conductors: Same metals as electrical conductors
- Applications: Heat sinks, cookware
Mechanical Properties
- Malleability: Can be hammered into sheets
- Ductility: Can be drawn into wires
- Mechanism: Layers slide without breaking bonds
- Non-directional bonding: Allows plastic deformation
Optical Properties
- Metallic luster: Shiny appearance
- Light interaction: Electrons absorb and re-emit light
- Reflectivity: Good reflectors
- Opacity: Do not transmit light
Key Improvements Made
- Fixed typo: “The y create…” → removed and corrected section
- Standardized capitalization (metals, non-metals)
- Completed missing sections for covalent bonding
- Ensured parallel structure across all bonding types
- Improved scientific precision without overcomplicating
- Removed redundancy and tightened phrasing
Intermolecular forces
In addition to primary chemical bonds, there are weaker forces that act between molecules, known as intermolecular forces. These forces influence the physical properties of substances, such as boiling and melting points, solubility, and viscosity.
They are responsible for properties such as the behavior of water, the ability of some substances to dissolve in others, and the states of matter (gases, liquids, and solids).
Since water (H₂O) is a polar molecule, it can form hydrogen bonds, which are a strong type of dipole–dipole interaction. This gives water its unique properties, such as high surface tension and a relatively high boiling point.
Similarly, molecules like NH₃ can also form hydrogen bonds. However, since ammonia is less polar than water, these interactions are weaker, resulting in lower boiling points and different physical properties.
Intermolecular forces also affect solubility. Polar substances tend to dissolve well in polar solvents (like water), while nonpolar substances dissolve better in nonpolar solvents (like oil). This is often summarized by the phrase "like dissolves like."