A chemical bond is the bond between atoms or ions through sharing or transfer of electrons. This attraction is courtesy the electrostatic force that exists between the electron(s) of one atom and proton(s) in the nucleus of the other atom. The energy required to break this bond is called bond energy or bond dissociation energy. When two atoms bond, the energy released is called negative bond energy. Electrons in the outer shell – called valence electrons – are the active participants in this bonding process, along with protons.

Why Do Atoms Bond?

An atom without sufficient electrons in its valence shell (outermost shell) and another atom with extra electrons in its valence shell are usually unstable (high or low energy state), which is not an atom’s normal state of being. Generally, atoms with equal number of protons and electrons are stable since they have equal amount of positive electric charges and negative electric charges.

However, when there’s a discrepancy, the atom becomes unstable or chemically reactive. To attain stability, the atom attaches itself to another atom either by losing electron(s) to the other atom, gaining electron(s) from the other atom, or sharing electron(s) with the other atom. This helps the atom attain stabilization or lose or gain energy, satisfying the octet rule in the process.

A chemical bond is a critical process in chemistry since it facilitates the creation of different molecules and atom combinations. The bond invariably results in the creation of a new molecule or compound. For example, when a sodium atom and a chlorine atom come together, the result is sodium chloride (table salt).

Chemical Bond Types

Chemical bonds can be primarily classified into an ionic bond, covalent bond and metallic bond.

  • Ionic bond: This is a bond courtesy electron transfer between oppositely-charged (positively and negatively charged) ions. For example, sodium ion (positive) and chloride ion (negative) bond with each other to create sodium chloride.
  • Covalent bond: A covalent bond exists when the electrons are shared between atoms and not transferred. Compared to an ionic bond, a covalent bond is more widespread in molecules of living organisms.
  • Metallic bond: This is a type of chemical bond that entails electrons shared by atoms of metallic elements.

The type of bond created varies with the element involved. Some other chemical bond types are hydrogen bond, dative bond, network covalent bond, etc.

Why Protons in the Two Atoms Do Not Cause the Atoms to Repel?

When atoms bond, there are multiple interactions or forces involved. The two atoms’ positively-charged nuclei repel each other. Similarly, both the atoms’ negatively-charged electrons repel each other. However, one of the atoms’ negatively-charged electron attracts the other atom’s positively-charged nucleus, and vice versa.

This attractive force between the nuclei and electrons is stronger or greater than the repulsive forces existing. This causes the atoms to bond. There are also instances when the total of the repulsive forces is stronger than or equal to the attractive force. In such cases, there is no chemical bond.

Breaking the Bond

A chemical bond can be broken by energy called bond energy or bond dissociation energy. For the bonds to stay together, energy must be released, which is basically referred to as negative bond energy. Bond lengths stay consistent and therefore the energy required to break the bond also is the same.