Chemical bonds are formed and broken during chemical reactions. The bonds between the atoms of the reactants are broken, then bonds between the atoms of products are formed. Chemical bonds are either ionic bonds (formed by electronic exchange between an electropositive and electronegative atom) or covalent bonds (electrons are shared between atoms). An example of bond formation and breaking is the burning of hydrogen to produce water.
2H2 + O2 -> 2 H2O
Here covalent bonds between oxygen atoms in oxygen gas and hydrogen atoms in hydrogen gas are broken. And covalent bonds are formed between hydrogen and oxygen atoms to produce water.
Chemical bonds also determine if a chemical will undergo a reaction or not. Bond formation and breaking may require or release energy and if not energetically favorable, bonds will not break or form and reaction will not take place.
Hope this helps.
We set apart in chemistry 3 main types of the bonds -
1) Covalent bonding (which is the most common, and the strongest) [it has subgroups - as polar and coordinate bonding ] [electronegativity difference between the bonded atoms is small or nonexistent]
2) Ionic bonding [electrostatic interaction between atoms which have a large electronegativity difference]
3) Metallic bonding - bonding electrons are delocalized over a lattice of atoms.
- Ionic bonds form between metals and nonmetals.
- Covalent Bonding - this most commonly occurs when two nonmetals bond together
- Metallic - between metals