Introduction

• scientists knew about three types of forces – gravitational, magnetic and electrostatic.
• They also knew about the existence of electrons and protons. So it was believed that electrostatic forces were the cause of attraction between atoms in a molecule.
• When two atoms come sufficiently close together, the electrons of each atom experience the attractive force of the nucleus of the other atom.
• But the electrons which are negatively charged and repel each other, and the positively charged nuclei also repel each other.
• The strength of attraction or repulsion will decide bond formation. If attraction is more than the repulsion then atoms combine
• If repulsion is more than attraction then the atoms do not combine. The nucleus and the electrons in the inner shell remain unaffected when atoms come close together. But the electrons in the outermost shell (valence shell) of atoms get affected.