1. How atoms are joined together

2. Atoms are made up of extremely small particles called Neutrons, Protons and Electrons. In an atom protons and neutrons will be present at the center of the atom called nucleus and the electrons will move around it in different zones called energy levels. The arrangement of electrons in different energy levels is called electronic configuration.

3. The animation illustrates the arrangement of electrons in different energy levels of an atom of Lithium

4. The halogen group elements will have 7 electrons in the outermost shell. Eg:The electronic arrangement in Fluorine with At No.9.

5. Except Helium, all inert elements have 8 electrons arrangement in their outermost shell.This octet arrangement makes them chemically inactive.All other elements tend to attain this stable structure of 8 electrons in outer shell, by bonding.

6. An atom can attain octet arrangement by forming two main types of chemical bonds namely Electrovalent bond Covalent bond

7. Formation of Electrovalent Bond or Ionic Bond Let us consider the formation of Sodium Chloride Electronic configuration of Sodium is 2,8,1 Electronic configuration of Chlorine is 2, 8, 7 Sodium is short of 1 electron and Chlorine is short of 7 electrons respectively to get octet arrangement When one electron is transferred from sodium to chlorine, the electronic configuration of both the elements will be 2,8 and 2,8,8 respectively.

8. Ions are formed when electrons are completely transferred from one atom to another. Sodium looses electron and becomes positive ion Chlorine gains electron and becomes negative ion The oppositely charged ions attract each other by electrostatic forces forming ionic bond

9. Sodium Chloride

10. . The concept of formation of an ionic bond is made clear in the following animation

11. When a compound is formed when two or more atoms chemically bond together, the resulting compound is unique both chemically and physically from its parent atoms. The element sodium is a silver-colored metal that reacts so violently with water that flames are produced when sodium gets wet. The element chlorine is a greenish-colored gas that is so poisonous that it was used as a weapon in World War I

12. When chemically bonded together, these two dangerous substances form the compound sodium chloride, a compound so safe that we eat it every day - common table salt! Sodium metalChlorine gasSodium Chloride salt + + Chemical Bonding changes the properties of the constituent atoms!