Question

What are two pairs of elements that are not arranged by increasing atomic mass when arranged by increasing atomic number.

Answer 1

whats the modern atomic law too?

Answer 2

Hi! @dahomie !
Modern atomic theory is also called Bohr's Thory. It states that the electrons are arranged in concentric circular orbits around the nucleus.

Answer 3

For the first qn, did u mean an example?

Answer 4

yes
I believe the answer is Cobalt and Nickel; Lawrencium and Rutherfordium
thx for youre help too @shreehari499 !!!

Answer 5

Hmm...yeah..anytime!