Ionic, Covalent, and Metallic Bonds
Table of Contents
Ionic, covalent, and metallic bonds are different types of chemical bonds. An ionic bond is formed when one atom donates valence electrons to another atom. A covalent bond is formed when both atoms share pairs of valence electrons. A metallic bond is formed between a cloud of free electrons and the positively charged ions in a metal.
In ionic and covalent bonds, the valence electrons play a critical role in forming the bond. Atoms achieve a stable electronic configuration by transferring and sharing electrons. As a result, the bonds become stable with well-defined strength and energy.
Ionic Bond vs. Covalent Bond vs. Metallic Bond | |||
| Ionic Bond | Covalent Bond | Metallic Bond | |
|---|---|---|---|
Occurs between | A metal and a nonmetal | Two nonmetals or a nonmetal and a metalloid | Positively charged ions and negatively charged electron cloud |
Formation | Electrostatic attraction between oppositely charged ions | Sharing pairs of electrons | Electrostatic attraction between the delocalized electron cloud and positively charged metal ions |
Formation between atoms of the same element | No | Yes | – |
Electronegativity difference between atoms | High (>2) | Low (<0.1) for nonpolar compounds and intermediate (0.1 – 2) for polar compounds | Electronegativity does not play any role |
Isomerism | Nondirectional | Directional | Nondirectional |
Physical state of compounds | Solid at room temperature | Liquid or gas at room temperature | Solid at room temperature |
Low melting and boiling points | High melting and boiling points | ||
Dissociate into ions in solution | Retain their molecular identity in solution | Some metals react vigorously with water, while others do not | |
Conductivity | Low in solid-state, but becomes high in molted state and solutions | Low, except conducting polymers | High |
Examples | Methane (CH4) and water (H2O) | Sodium (Na) and potassium (K) | |
Similarities between Ionic and Covalent Bonds
- Valence electrons participate in bonding
- Form neutral, stable compounds
- Compounds are formed through exothermic reactions
- Compounds have faster rates of reactivity
- Ionic compounds are always polar. Some covalent compounds are also polar.
- Ionic compounds are crystalline. Some covalent compounds are also crystalline.
Similarities between Ionic and Metallic Bonds
- Involve electrostatic attractions
- Metallic bond has high thermal and electrical conductivities. The ionic bond can have high conductivities in molten states and solutions.
- Ionic compounds and metals have high melting and boiling points.
- Ionic compounds and metals are solid at room temperature
Similarities between Covalent and Metallic Bonds
- Metals are solid at room temperature. Some covalent compounds are solid at room temperature.
