KEY2CHEM

Types of Chemical Bonds 

The type of chemical bond formed between two atoms depends on the nature of each atom in the bond. Ionic bonds generally form between a metal and a nonmetal and result from a transfer of an electron from the metal to the nonmetal. Covalent bonds generally form between nonmetals and result from a sharing of electrons between the atoms. Metallic bonds generally form between metallic atoms, with the valence electrons delocalized in a “sea” around the metallic cations.


Example 1.

What is the major type of bonding in \(\require{mhchem}\ce{NaCl}\)?

A. ionic

B. covalent

C. metallic

 

Solution 

A. ionic

Sodium is a metal and chlorine is a nonmetal. As such, ionic bonding is expected to be the major type of bonding interaction between these particles.


Example 2.

 

What is the major type of bonding in \(\require{mhchem}\ce{Ag(s)}\)?

A. ionic

B. covalent

C. metallic

 

Solution

C. metallic

In a metal, such as \(\require{mhchem}\ce{Ag}\), the valence electrons are delocalized in an “electron sea” surrounding the metallic \(\require{mhchem}\ce{Ag}\) cores (nuclei plus inner electrons).


Example 3.

 

What is the major type of bonding in \(\require{mhchem}\ce{H2O}\)?

A. ionic

B. covalent

C. metallic

 

Solution

B. covalent 

Hydrogen and oxygen and both nonmetals, so covalent bonds are expected to form. Because hydrogen and oxygen have different electronegativity values, the \(\require{mhchem}\ce{H-O}\) bonds in water are polar covalent bonds (unequal sharing of electrons).