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Ionic, Covalent, and Metallic Bonds

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 BondCovalent BondMetallic Bond

Occurs between

A metal and a nonmetal

Two nonmetals or a nonmetal and a metalloid

Positively charged ions and negatively charged electron cloud


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



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





Physical state of compounds

Solid at room temperature

Liquid or gas at room temperature

Solid at room temperature

Physical properties

High melting and boiling points

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


Low in solid-state, but becomes high in molted state and solutions

Low, except conducting polymers



Sodium chloride (NaCl) and potassium iodide (KI)

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.
Ionic vs Covalent Bonds

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
Ionic and Metallic Bonding

Similarities between Covalent and Metallic Bonds

  • Metals are solid at room temperature. Some covalent compounds are solid at room temperature.
Covalent and Metallic Bonding