But here we should not forget a most fundamental truth . After the big bang matter was being thrown to all side at terrible speed. The outward movement of matter, the gigantic scale expansion , is still continuing .All further changes like formation of galaxies and formation of millions of stars inside each galaxy is occurring in this ever expanding matter to this day. This expansion is going on even 14 billion years after the big bang! The processes from birth to death of stars and galaxies, the implosions and explosions etc are occurring in one or the other galaxy even now!
The galaxies and stars with white hot cores were forming with temperatures of tens of millions degrees in their cores. Such environment in cores of stars is necessary to make the thermonuclear reactions( fusing hydrogen nuclei into nuclei of higher chemical elements) self sustaining.The outer surfaces of stars were comparatively cool at around ten thousand degrees kelvin. But matter even on surface of these nebulous stars is always in the plasma state.—a white hot gas-like state in which only the nuclei of chemical elements existed in billions and billions of tons. This is the state of every one of the billions of stars in each galaxy. The sun is also a star at the peripheral portions of our wheel like galaxy called Milky Way. To travel even to the star next to the sun we require a nonstop journey of one hundred thousand years by a rocket travelling at 50000 kilometers an hour .There are billions of such stars in our galaxy and there are billions of galaxies in the universe!
Now let us return to our earth ( earth is so small that if we compare sun to a foot ball earth would be the size of a very small pea circling at about 30 yards from it.!)
Now let us study the condition of earth a few billion years back after all the above cataclysmic changes were completed. The sun has always been a fiery plasma ball spinning at great speed. A few pieces of the plasma ball of sun got loose at the edges and slipped a little distance away( a few hundred million miles away!) But due to the terrible power of gravity the pieces continued to circle the sun..
The hot pieces of plasma which got loose from the sun slowly cooled for hundreds of million years and became planets. The force of gravity makes them circle around sun forever. . As temperatures completely cooled (due to vast distance from sun which is the source of all heat coming to planets),electrons attached themselves to the nuclei existing on the fast cooling plasma pieces(which became the planets) and neutral atoms of the 92 elements appeared in solid ,liquid and gaseous forms. the changes were similar on all the planets . But in beginning every thing was too hot and even metals existed in vapor state . Solid and liquid forms of chemical elements and chemical compounds formed only after hundreds of thousands of years.as far as earth was concerned all chemical reactions took place in the water- and- oxygen dominated environment earth and especially in its oceans…