Answer:
I think it might be elements and compounds! I may be wrong though.
Answer:
atomic number
Explanation:
The periodic table is a table that lists all of the chemical elements in order of atomic number, starting with hydrogen and ending with oganesson. The number of protons in the nucleus of an atom of a certain element is its atomic number.
Have a good day :)
Something that breaks with little force against it.
Answer:
democritus is the first person
