Question

Main topic in structure of an atom chapter

Answer 1

The lesson's name itself says
Main topic of this chapter is STRUCTURE OF AN ATOM and its models historically.
Then,
The Atomic number, Mass number, etc., of an element.




Hope this will help you. 

If you like my answer
Please mark it as brainliest 
And 
Be my follower if possible.

Answer 2

discovery sub atomic particles
models of different scientists and their limitations and observations
isotopes
valency of elements.......