The original question: Are all the protons, electrons, and neutrons identical, and only the number of protons in the nucleus of the atom determines what element it will be?
The original question: Are all the protons, electrons, and neutrons identical, and only the number of protons in the nucleus of the atom determines what element it will be?
Indeed, there is no difference between one proton and another, one electron and another, or one neutron and another. Without getting into the spin issue, they are identical. An element and its location in the periodic table is determined according to the number of protons in the nucleus.
The periodic table. All rights reserved Encyclopedia Britannica
The electrons influence the atom’s electric charge. An atom that is not electrically balanced, that is, an atom with a different number of electrons and protons, is called an ion, and its charge depends on the lack or excess in the number of electrons in comparison with the number of protons.
The number of neutrons influences the element’s mass; that is how isotopes of the same element differ. For instance, hydrogen’s known isotopes are normal hydrogen, marked as H or H1; heavy hydrogen, also known as deuterium, marked D or H2; and tritium, marked T or H3. They all have one proton, but deuterium also has a neutron, and tritium has two neutrons. One element that is well known, due to its isotopes and use in nuclear processes, is uranium, marked U, which has six main isotopes. They all have 92 protons, of course, but differ in the number of neutrons.
Most prevalent among them in nature is 238U, but there’s also 236U, 235U, 233U, 232U. The number to the left is the mass number and it describes the number of protons and neutrons, that is, the nucleon number. To calculate the number of neutrons, subtract the atomic number (which equals the number of protons) from the mass number.
By: Dr. Liran Shimshi
Department of Physics of Complex Systems
Weizmann Institute of Science