In chemistry, a bond is an attachment between atoms. Bonds form because atoms are made of particles with electrical charges. The center of an atom contains particles with a positive charge, and particles with no charge. The particles around the outside of an atom each have a negative charge. Have you heard the saying “opposites attract?” It applies in chemistry, too. The attraction between negative charges in one atom and positive charges in another is the basis for a chemical bond
Chemical bonds between individual atoms form molecules. Bonds can also form between the atoms in molecules and other atoms or molecules nearby. Chemical bonds form every solid thing on Earth — from huge boulders to the cells in your body.
There are many kinds of chemical bonds. All of them require energy to form, and energy to break. Every chemical reaction involves a change in chemical bonds as atoms get added or removed from molecules. That’s why all chemical reactions involve energy.