phosphorus
Among these three elements, Cl has the greatest mass, as can be seen from any periodic table or other reference work that shows atomic masses.
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.
Among these three elements, Cl has the greatest mass, as can be seen from any periodic table or other reference work that shows atomic masses.
Generally the term "atomic mass" is used for isotopes. For elements is preferred now "atomic weight".
The element Ununoctium, Uuo, has an atomic mass of 293.
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.
When Mendeleev developed his periodic table, he placed the greatest emphasis on organizing the elements based on their atomic masses and grouping elements with similar properties together. He also left gaps for undiscovered elements and predicted their properties.
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.
Iron is a metal element. Atomic mass of it is 55.84.
I suppose that you think to atomic weights (not mass) of chemical elements and the molecular mass.
Mendeleev arranged the elements in the periodic table according to their atomic masses.