Which element is considered to have the atomic number of 1?

Hydrogen is considered to have the atomic number of 1 because it is the simplest and lightest element on the periodic table. The atomic number of an element is defined by the number of protons in the nucleus of its atoms. Since hydrogen has one proton, its atomic number is 1. This characteristic makes hydrogen the first element in the periodic table, setting the foundation for all other elements, which have higher atomic numbers based on the number of protons they contain. In contrast, oxygen, nitrogen, and carbon have higher atomic numbers, reflecting their greater number of protons in their nuclei, which classifies them differently from hydrogen.