The atomic mass of an atom of hydrogen is approximately 1.008 atomic mass units (amu). This value represents the average mass of hydrogen atoms, taking into account the different isotopes of hydrogen and their relative abundance.
Hydrogen has three isotopes: hydrogen-1 (1H), deuterium (2H), and tritium (3H). The most common isotope is hydrogen-1, which consists of a single proton and no neutrons. Deuterium has one proton and one neutron, while tritium has one proton and two neutrons.
The atomic mass of hydrogen is influenced by the relative abundance of its isotopes in nature. The vast majority of hydrogen atoms are hydrogen-1, with a small fraction being deuterium and an even smaller fraction being tritium. Since hydrogen-1 is the most abundant isotope, its mass of approximately 1.008 amu dominates the average atomic mass of hydrogen.
In terms of its position on the periodic table, hydrogen is located in Group 1 and Period 1. It is unique because it is the only element that does not fit neatly into any particular group or category. Its position reflects its atomic number of 1, indicating that it has one proton in its nucleus. However, the atomic mass of hydrogen is higher than other elements in Group 1, such as lithium, sodium, and potassium. This is due to the presence of the heavier isotopes, deuterium and tritium, which contribute to the average atomic mass of hydrogen.