Question: There is a typical construction that I do not know specially when concerning about movements, in which we use the preposition y instead of the subject?

Answer: 
The phrase *у меня есть* means possession = *я имею* (I have). Your sentence contains this phrase in the future tense *у меня будет* (I will have, I am having). The sentence should be:

> 
> После русского языка у меня будет химия (лекция по химии).
> 
> 
> 

You can use another verb to describe your action.

> 
> После (урока) русского языка я пойду на лекцию по химии.
> 
> 
> 

("Я буду на лекции" is understandable too, but sounds a bit clumsy.)
The following article explains your subject rather well:

<http://masterrussian.com/aa120199a.shtml>

Your example, in particular, has a direct English analogy: *I have Chemistry after Russian* sounds quite regular.