General chemistry Relative atomic masses
As is known, in the periodic table of Mendeleev, the relative atomic masses of the elements are arranged in ascending order. But there are cases when the preceding element has a relative atomic mass greater than that of the next one after it. How many such cases are there and why is this happening?
A very interesting question. The fact is that the table we use is now slightly changed and based on the atomic number, not the mass. That's why some elements "jumped"
Unfortunately, I can't say exactly how many such elements, but you can easily look at the table and find out
Thank you, argon and potassium, cobalt and nickel, tellurium and iodine.
That's an interesting fact! You don't have much apportunities to surprise people with periodic table, and yet here we are)