Covalent bonding typically occurs between non-metallic elements. These elements have a relatively high electronegativity, which means they have a strong attraction for electrons. When two non-metallic elements come close together, their outer electrons can be shared between the two atoms, creating a covalent bond.

Some examples of covalent bonds include:

- Hydrogen (H) and hydrogen (H)

- Carbon (C) and carbon (C)

- Nitrogen (N) and nitrogen (N)

- Oxygen (O) and oxygen (O)

- Fluorine (F) and fluorine (F)

Covalent bonds can also occur between two different non-metallic elements. Some examples include:

- Hydrogen (H) and chlorine (Cl)

- Carbon (C) and oxygen (O)

- Nitrogen (N) and hydrogen (H)

- Oxygen (O) and hydrogen (H)

- Fluorine (F) and hydrogen (H)

In general, covalent bonds are stronger than ionic bonds. This is because the electrons in a covalent bond are shared between the two atoms, while the electrons in an ionic bond are transferred from one atom to another.