Question

On the basis of orbital concept , explain the formation of F2 ,HF ,H2O

Answer 1

To construct a MO for a diatomic molecule, you must first write down the atomic orbitals of each atom and organize them by energy levels.  For instance, for O2 you write down all the atomic orbitals (which are 2p and 2s orbitals) and list them from highest (on top) to lowest energy levels.  Next, you will create the MOs from atomic orbitals, making sure the number of MOs equal the number of atomic orbitals and for each pair of atomic orbitals there is one bonding MO and on anti-bonding MO (bonding MOs are lower in energy than anti-bonding MOs).  The last step is to fill in the MO's with the valence electrons from both atoms.  

By looking at the orbital diagram, we can see that oxygen has BO of 2 because it has 10 bonding and 6 antibonding, very stable. It's paramagnetic because it posses 2 unpaired electrons.

For Difluorine, by counting the number bonding, 10, and number of antibonding, 8, give us the BO of 1. It is diamagnetic with no unpaired electrons.

The difference between molecules on the questions 1 and 2 are introduced somewhat at the beginning of the topic. It basically is the mixing between orbitals of similar symmetry and energy, and the result turns out to be different compare with F2 and O2. As you can see from the MO diagram show on for all of these two cases, the energy of O2 and F2 have bi-bond higher energy than sigma-bond of the 2p orbital. This is also called sigma-bi crossover between N2 and O2.

BE YOURS............^_^

Answer 2

Answer:

(i) Formation of F, molecule: Fluorine atom has one half-filled atomic orbital. Therefore, two atoms of fluorine combine to form the fluorine molecule.

(ii) Formation of HF molecule: HF molecule is formed as a result of the combination of half-filled orbitals belonging to hydrogen and fluorine.

(iii) Formation of O2 molecule: Each oxygen atom has two half-filled orbitals. Two such atoms will combine a molecule of O2.

(iv) Formation of H2O molecule: Oxygen has two half-filled orbitals. Thus, it combines with two hydrogen atoms.

(v) Formation of N2 molecule: Each nitrogen atom has 3 half-filled orbitals. Thus, two nitrogen atoms combine to form triple bond.