1) Principles of Chemical Bonding

                                               Types of Chemical Bonding
                 There are three types of chemical bonding which are give below
                    a) Covalent Bonds
                    b) Ionic Bonds
                    c) Polar Covalent Bonds 
                                            

   a) Covalent Bonds

Don't look now, but you're surrounded by covalent bonds. They're in the air you breathe and in the water you drink. You even make them yourself when you exhale. What are these bonds? What do they want?

Covalent  atomic bonding occurs when atoms share electrons. As opposed to ionic bonding in which a complete transfer of electrons occurs, covalent bonding occurs when two (or more) elements share electrons. Covalent bonding occurs because the atoms in the compound have a similar tendency for electrons (normally to gain electrons). This most commonly occurs when two nonmetals bond together. Because both of the nonmetals will desire to gain electrons, the elements involved will share electrons in an effort to fill their valence shells. A superior example of a covalent bond is that which occurs between two hydrogen atoms. Atoms of hydrogen (H) have one valence electron in their first electron shell. Since the capacity of this shell is two electrons, each hydrogen atom will "want" to pick up a second electron. In an effort to pick up a second electron, hydrogen atoms will react with nearby hydrogen (H) atoms to form the compound H2. Because the hydrogen compound is a combination of equally matched atoms, the atoms will share each other's single electron, forming one covalent bond. In this way, both atoms share the constancy of a full valence shell.

A molecule of water consists of an oxygen atom that is bonded to two hydrogen atoms.. These two valence electrons forming the bond are shared by both atoms, resulting in a

SINGLE COVALENT BOND. Think of this in terms of two pieces of wood that are nailed together. The pieces of wood are the atoms, and the nails holding them together are the electrons that form the covalent bond. Each piece of wood shares a portion of the nails. A hydrogen atom and the oxygen atom each donate one valence electron to form a chemical bond Take a look at water (H2O). H2O is a MOLECULE, a discrete unit of atoms that are bonded together

.

Air, too, contains oxygen. Oxygen does not exist as a only oxygen atom, but as a molecule of two oxygen atoms. These two oxygen atoms contribute to two pairs of valence electrons (four valence electrons total) between them, forming a DOUBLE COVALENT BOND. This is right of any double covalent bond; four valence electrons

are shared between two atoms..

a new component of air is nitrogen. similar to oxygen, nitrogen does not live as a single nitrogen atom, but as a molecule made up of two nitrogen atoms. The two nitrogen atoms in a molecule of nitrogen share three pairs of valence electrons (six valence electrons total) to form a TRIPLE COVALENT BOND.

Is it likely to predict whether bonds are covalent or not? A good law of thumb is that bonds between nonmetals (remember that hydrogen is considered a nonmetal) are usually covalent bonds. For example, the carbon dioxide (CO2) molecules you exhale are bonded jointly covalently.

So you observe, you are surrounded, but it's okay. Calm down. Take a deep breath. Get a drink of water, possibly. Then read on to learn about some other ways molecules stick collectively.