Which element has the lowest atomic number?

Which element has the lowest atomic number?

• A. Oxygen
• B. Hydrogen
• C. Carbon
• D. Helium

Answer: (B)

Hydrogen has the lowest atomic number of all the elements, which is 1. The atomic number represents the number of protons found in the nucleus of an atom of that element. Since hydrogen is the simplest and lightest element, it consists of just one proton and one electron, making it unique on the periodic table. In contrast, oxygen has an atomic number of 8, carbon has an atomic number of 6, and helium has an atomic number of 2, all of which are higher than that of hydrogen. Therefore, hydrogen's position at the top of the periodic table confirms it as the element with the lowest atomic number.

Hydrogen has the lowest atomic number of all the elements, which is 1. The atomic number represents the number of protons found in the nucleus of an atom of that element. Since hydrogen is the simplest and lightest element, it consists of just one proton and one electron, making it unique on the periodic table. In contrast, oxygen has an atomic number of 8, carbon has an atomic number of 6, and helium has an atomic number of 2, all of which are higher than that of hydrogen. Therefore, hydrogen's position at the top of the periodic table confirms it as the element with the lowest atomic number.