Question

plz someone, its science​

Answer 1

Answer:

Explanation:

1.he left gaps stating that new elements will be found and he also predicted its properties which were came to be true

2.Mendeleev could not determine the accurate position of the hydrogen atom in his table.

This is because hydrogen’s characteristics are very similar to halogens and alkali metals.

Other key limitations in Mendeleev periodic table were that the atomic number in the table was not shown increasing in a regular pattern and the symmetry of the table was also disturbed.

3.electronic configuration

when going across a  period new electrons are added but the shell remains the same

when going down a group no of valence electrons are same but there is a difference in no  shell

hope you got it !!!!!!!!!iiiiiii