Question

The lightest element is ______

Answer 1

In the modern periodic table (or long form of the periodic table), the elements are arranged in the increasing order of their atomic number. In the table, an element is represented as ${\mathrm{X}}_{\mathrm{A}}^{\mathrm{Z}}$.

where Z is the atomic mass

and A is the atomic number.

Atomic mass

The average atomic mass of an element is given by the sum of the number of protons and the number of neutrons. This is because the mass of an atom is concentrated in the nucleus.

Among all the elements in the periodic table, Hydrogen consists of 1 proton and zero neutrons which correspond to an atomic mass of 1.

Hence, The lightest element is Hydrogen (H)