Question

Why can't atoms exist independently while molecules can exist independently?

Answer 1

Some exits like noble gases like HELIUM who have valency 0.
While atom who don't have 8 electrons in there other most orbit will tries to make 8or 2 elections in there outermost orbit by giving and taking electron i.e by making molecules or compounds eg take lithium which have 3 electron hence its valency is 1 so in order to make 2 or 8 in its outermost orbit it have accept 7 or lose 1 electron but 1 electron is easier…
Atoms which loses forms positive ion while which accept will form negative.
Now eg take oxygen which have - 2 valency so it want 2 electron. Now if there are 2 lithium each give 1–1 electron. So oxygen will accept both electron and both 2 lithium and 1 becomes ion, one positive and one negative respectively. As we know opposite charges attract each other. Hence bond is form.
But there various bond like ionic bond and covalent bond (I have taken eg of ionic).
But there are also cases where Nobel gases i.e helium even being Noble will form bond with hydrogen, HELIUM hydride.
Hope it will help you
Your teacher.