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 refers to the number of protons found in the nucleus of an atom of that element. In the case of oxygen, its atomic number is 8, meaning it has 8 protons in its nucleus. This is the fundamental property that defines the element as oxygen and distinguishes it from other elements on the periodic table. The atomic number also indirectly determines the number of electrons in a neutral atom. In a neutral oxygen atom, there are 8 electrons to balance the 8 positive charges from the protons, ensuring the atom is electrically neutral.
The number of protons in an atom is the key factor in defining the element. For example, if an atom has 8 protons, it must be oxygen. If it has 6 protons, it would be carbon. This concept is central to the structure of the periodic table, where elements are organized based on their atomic numbers.
The electron configuration of oxygen also plays a role in its chemical behavior. Oxygen has 8 electrons, which are arranged in two electron shells. The first shell contains 2 electrons, and the second shell contains 6 electrons. The second shell can hold a maximum of 8 electrons, which means oxygen is two electrons short of achieving a full, stable outer shell (the octet rule). This is why oxygen is highly reactive and tends to form bonds with other elements to complete its outer electron shell, often by gaining, losing, or sharing electrons.
While the atomic mass of oxygen is approximately 16 (which is the sum of protons and neutrons), the atomic number is based solely on the number of protons. The statement about oxygen having a second shell with 8 electrons refers to a different characteristic, but it is not the reason for its atomic number being 8.
In conclusion, the atomic number of oxygen is 8 because it has 8 protons in its nucleus.