[Ashishkumar]

 My name is Ashish R. Sai Im from India.I just went through the some basic concepts of chemistry. I just got damn confused "How the two atoms can make bonds when both got electrons in there outer most layer electrons got same charge and same charge repel each other.So how can they come closer to each other??

[ramboacid]

If you think about it for a bit, usually bonding is more energetically feasible than remaining as free atoms. For example, take salt: sodium and chlorine atoms are in lower energy states in a crystal lattice than as free metal and gas. Overall, the net change in energy is negative an the compound is more stable.

How do they get close enough? Well, I suspect there may be an activation energy barrier of some sort. In ionic compounds, you can make a graph of potential energy vs distance separated. There's a good article with a picture on this:
http://www.sparknotes.com/chemistry/bonding/ionic/section1.html

[Proton]

Bonding orbitals are always lower in energy than the atomic orbitals they're derived from, because the electrons are attracted to two nuclei. The increased coulombic attraction experienced by the bonding electrons is stronger than the electron repulsion and thus there is an overall decrease in orbital energy which increases the overall entropy. So thermodynamically bonding must occur.

[dipesh747]

If you look at this (rough) diagram. Potential energy is the y axis and distance is the x axis. This is a potential energy curve.

Say you have 2 H atoms you can see when they are far apart they are lower in energy than the H2 molecule. As they get closer together there is a critical point where the two curves intercept. At this point it is lower in energy to become the H2 molecule and follow the curve to its lowest point (the well).

The reason behind this diagram:

At long range distances there attraction between the 2 atoms, due to van der walls forces.
These forces push these molecules together and they then react to form H2 (as it is lower in energy).
The molecule then sits in the potential energy well.
You can see from the diagram that the atoms, when they are in this well, cannot go closer together as the potential energy increases (this is due to short range repulsion).
Once the atoms have bonded they will need significant energy to then break apart (i.e. go back onto the 2H diabatic curve)


(I don't know if this diagram is strictly correct, but the ideas underlying are sound)

[manonemission]

Someone please correct me if I am wrong but I thought it was related to the relative emptiness of the outer shell.  I envision the outer shell/orbital as having more 'play' in terms of where the electrons concentrate.  Thus, if there are less than eight electrons, they can concentrate more on one side or the other, so London dispersion force can occur, where the repulsion of the electrons from nearby atoms causes them to move toward the end of the atoms furthest from one another.  Is this an incorrect assumption?

[vansh123]

it is easy to explain
1) they have got the same number of valance electrons so they combine and form a covalent bond in which they share the electrons of the other atom with their and vice versa.

2)they get attracted because of the nuclei:
the electrons of one atom are attrachted by the nucleus of the other atom and vice versa this is because of
same charge repel each other and opposite attract each other

If im wrong then please correct me
Thanks

[vansh123]

Sorry the part 2) was wrong
the electrons are attracted by both the nuclei