Rutherford's nuclear model of the atom presented a few key principles about atomic structure, largely derived from the gold foil experiment. Let us understand each statement given in the options related to Rutherford's model and determine which one is not true:
Protons and neutrons are present inside the nucleus: This statement is indeed true in the context of atomic models. According to modern understanding, protons and neutrons (nucleons) are present in the nucleus of an atom. However, Rutherford's model specifically identified only the protons, as neutrons were discovered later by James Chadwick in 1932.
Volume of nucleus is very small as compared to volume of atom: This is a fundamental aspect of Rutherford's model. The gold foil experiment revealed that most alpha particles passed through the foil, indicating that the nucleus occupies a very small volume compared to the overall size of the atom.
The number of protons and neutrons are always equal: This statement is not true and is the correct answer. The number of protons (atomic number) does not always equal the number of neutrons. Different isotopes of the same element have different numbers of neutrons, while their proton number stays constant.
The number of electrons and protons are always equal: This is generally true for a neutral atom, where the positive charge of the nucleus (from protons) is balanced by the negative charge of electrons.
The correct answer is that "The number of protons and neutrons are always equal" is not true, as isotopes exhibit a variation in the neutron count while having the same proton count.
Which of the following is the correct electronic configuration for \( \text{Oxygen (O)} \)?