The other positive is that you could learn to find the answer to any question that is posed to you.
Demitri Mendeleeve (Russian – 1869) was published the first periodic table, based on atomic mass.
here also focus on Periodic Law: modern periodic table organized according to atomic number.
What is the total number of protons in the nucleus of an atom of potassium-42?
Compared to the nonmetals in Period 2, the metals in Period 2 generally have larger 1.