Hydrogen and Helium
No two elements may have the same atomic number. But two elements may have same atomic mass. Hence atomic number is better than atomic mass.
By Atomic Mass
Gold is a meta element. Atomic Mass of it is 197.
Atomic Mass.
Mendeleev's version of the Periodic Table was organized by increasing mass. The modern periodic table is now organized by atomic number.
On the periodic table, the elements are arranged by Atomic Mass. Helium and Hydrgen are at the way top of the table due to how they have the smallest amount of mass. The elements with the biggest mass are at the bottom.
Elements were originally placed in order of atomic massnow they are placed in order of atomic number
Generally the term "atomic mass" is used for isotopes. For elements is preferred now "atomic weight".
No two elements may have the same atomic number. But two elements may have same atomic mass. Hence atomic number is better than atomic mass.
Hydrogen
Hydrogen
Hydrogen.
Hydrogen.
By Atomic Mass
The molar mass of a compound is the sum of atomic weights of the contained elements in the molecule.The expression atomic weight is correct for elements; for isotopes is correct atomic mass.
Gold is a meta element. Atomic Mass of it is 197.
Atomic Mass.