Hydrogen
hydrogen
Helium is the second lightest element on the periodic table, with an atomic number of 2 and an atomic weight of approximately 4.0026 atomic mass units.
Hydrogen is the least massive (lightest) chemical element. It has an atomic mass of '1'
Dalton used hydrogen as his standard for atomic mass because it is the lightest element and was convenient for comparing the masses of other elements.
hydrogen has the least mass of all the elements, so yes in a way, it is.
hydrogen
Hydrogen.
Technetium which has an atomic mass of 98.
We would need to know which average you need in order to answer this question.
Hydrogen is the lightest element, with an atomic number of 1. Its low atomic mass and simple structure make it the lightest element in the periodic table.
Lithium is the lightest element metal with a relative atomic mass of 7 (3 protons, 4 neutrons).
From the Periodic Table The 'first element' is ;- Atomic No. 1. . which is Hydrogen (H) It has an atomic mass of '1'