Question

state modern periodic law. How many groups. and periods are present in modern periodic law?

Answer 1

Using atomic number instead of atomic mass as the organizing principle was first proposed by the British chemist Henry Moseley in 1913, and it solved anomalies like this one. Iodine has a higher atomic number than tellurium - so, even though he didn't know why, Mendeleev was right to place it after tellurium after all!
there were 18 groups and 7 periods in the periodic table

Answer 2

heya your answer!!!!

the modern periodic law was discovered by
Henry Moseley

the physical and chemical properties of the elements are the periodic functions of their electronic configuration.
the horizontal rows in the periodic table are called periods. there are 7 periods
the vertical columns in the periodic table are called groups. there are 18 groups