Electron Shells and Bonding


The electrons in an atom are arranged in Shells around the nucleus. These shells are also known as electron Orbital or Energy Levels.

  • The Lowest energy level is always filled first - the most inner shell.

  • Each shell can hold only a limited number of electrons

  • The first shell can only hold 2 electron - lowest energy level.

  • The Second shell up to 8 electrons.

  • The Third can also hold up to 8 electrons etc.

  • Atoms with their outer shell full of electrons, do not react with anything.  They are very stable.

  • Most atoms do not have their outer shell full of electron and this is what makes them want to react

  • Shell Fill


    Atomic Bonding:

    Other then the NOBLE GASES, the atoms of all other elements have incomplete outer shells.  That is why they react.   For any atom to become stable it must have its outer shell full of electrons  8 of the with the exception of Hydrogen and Helium, which only require 2 electrons. They can do this in two different ways:

    • By losing or gaining electrons or - ionic bonding

    • By sharing electrons - covalent bonding

    Ionic Bonding - it is all about atoms losing or gaining electrons to become stable, i.e. (have their outer shell full of electrons).

    • Remember !  A full outer shell makes an atom stable.


    Some facts:

    • During ionic bonding, atoms  gain or lose electron(s) to form stable negatively (-Ve) or positively (+Ve) charged ions which are then strongly attracted to one another to form an IONIC BOND.

    • Ionic bonds form between metals and non-metals.

    • Most metallic elements lose electrons to form a POSITIVE ION.

    • Most non-metallic elements gain electrons to form a NEGATIVE ION.

    • An ION is a charged particle (not an atom any more).  It is charged because it contains an unequal number of protons and electrons.

    Let's look at sodium chloride as an example:


    Water Bond:


    Tags:Water bond, Ionic bond, Atomic bonding, Electron Shells, Bonding, Atomic bonding, how do atoms bond, ionic bonds form between molecules that have, chemical bonds ionic bonds, how are ionic bonds form, electron bond, ionic bond, covalent bond



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