Which statement best explains why hydrogen's atomic number is equal to its mass? (1 point)

Question

• Hydrogen does not have any neutrons.
• Hydrogen only has one electron.
• Hydrogen is in the first row and the first column of the periodic table.
• Hydrogen is stable, with two electrons in its outer shell.

Answer 1

The statement that best explains why hydrogen's atomic number is equal to its mass is:

• Hydrogen does not have any neutrons.

This is because the atomic number of an element is equal to the number of protons it has, which for hydrogen is 1. Hydrogen typically has an atomic mass of about 1 amu (atomic mass unit) because it has one proton and no neutrons. In other isotopes of hydrogen, such as deuterium and tritium, the atomic mass differs due to the presence of neutrons, but the most common isotope, protium, consists of just one proton.