MCQ Detailed View

Atoms are made of protons, neutrons, and electrons. Protons and neutrons are located in the nucleus, while electrons move around the nucleus in orbitals. The number of protons in the nucleus is called the atomic number and defines the element. Neutrons, along with protons, contribute to the mass of the atom.

The sum of protons and neutrons in an atom is referred to as the nucleon number. It is also commonly called the mass number. The mass number represents the total number of nucleons in the nucleus and is a key property in identifying isotopes. For example, carbon-12 has 6 protons and 6 neutrons, giving a mass number of 12. Carbon-14 has 6 protons and 8 neutrons, giving a mass number of 14.

The atomic number only counts protons and does not include neutrons. Therefore, it does not represent the total number of nucleons. Nucleon number and mass number are used interchangeably in many contexts to describe the total nuclear composition.

Understanding the difference between atomic number and mass number is important in chemistry, especially when studying isotopes, nuclear reactions, and atomic structure. Mass number is also essential for calculating the relative atomic mass of elements, which is widely used in chemical calculations and formulas.

Both nucleon number and mass number provide the total number of protons and neutrons. This knowledge is foundational in physical chemistry and helps explain the behavior of atoms in chemical reactions and nuclear processes.