Protons are about 99.86% as massive as neutrons according to the Jefferson Lab. The number of protons in an atom is unique to each element.

Neutrons are neutral, as its name implies. A stable atom has a net charge of 0. In other words, it has an equal number of protons and electrons. The positive protons cancel out the negative electrons.

Given that protons are subatomic particles at the very heart of an atom, they are therefore extremely small, measuring just hundreds of trillionths of a meter (10^–15 meters).

Mass number and atomic number Protons and neutrons are the heaviest particles in an atom and as a result they make up most of the mass of the atom. The mass of electrons is often not considered to ...

The number of protons in an atom of any given element is always the same. Physicists call this the atomic number.

Atomic Number and Atomic Mass Atomic Number: The atomic number of an atom is determined by the number of protons it has. It uniquely identifies each element on the periodic table.

The number of protons is what defines the element, i.e. an atom with six protons in its nucleus will always be carbon, and uranium will always have 92 protons.

As they studied atomic disintegration, they kept seeing that the atomic number (number of protons in the nucleus, equivalent to the positive charge of the atom) was less than the atomic mass ...

This is a strontium atom, which has 38 protons; the diameter of a strontium atom is a few millionths of a millimeter.

Each distinct chemical element is characterized by a specific number of protons, but can have varying numbers of neutrons. These different versions of an element are called isotopes.