The atomic number of oxygen is 8 because oxygen has?
8 protons in the nucleus.
electrons in 8 shells.
a second shell with 8 electrons.
an atomic mass of 8.
The correct answer and explanation is :
The correct answer is 8 protons in the nucleus.
Explanation:
The atomic number of an element is defined as the number of protons present in the nucleus of an atom of that element. In the case of oxygen, the atomic number is 8, which means that each oxygen atom contains 8 protons in its nucleus. The number of protons is fundamental because it determines the chemical identity of the element.
For oxygen, the presence of 8 protons distinguishes it from all other elements. This atomic number is unique to oxygen, which means that no other element has exactly 8 protons in its nucleus. The number of protons in an atom’s nucleus is directly related to its position on the periodic table. Oxygen’s atomic number of 8 places it in the second period and the 16th group of the periodic table.
The number of protons also indirectly determines the number of electrons in a neutral atom. In a neutral oxygen atom, the number of electrons is equal to the number of protons, so it will have 8 electrons orbiting the nucleus. These electrons are arranged in energy shells or orbitals. The first shell holds 2 electrons, and the second shell, which is the outermost shell for oxygen, holds 6 electrons, filling the second shell to a total of 8 electrons.
The atomic mass (or atomic weight) of oxygen, which is typically around 16, is a different property. It is the sum of the protons and neutrons in the nucleus. Oxygen has an atomic mass of approximately 16 because it typically has 8 protons and 8 neutrons. However, atomic mass does not determine the atomic number, which is why the correct answer to this question is the number of protons, 8 protons in the nucleus.