69
The mass of an atom is primarily contained in its nucleus, which is made up of protons and neutrons. Electrons, which have a much smaller mass compared to protons and neutrons, occupy the space surrounding the nucleus.
Protons and Neutrons.
Protons and neutrons are contained within the nucleus of an atom. The nucleus is located at the center of the atom and it is where most of the atom's mass is concentrated. Electrons, which are negatively charged particles, orbit around the nucleus in electron shells.
Protons and neutrons. Virtually all of the atom's mass.
Neutrons
Neutrons
When calculating the mass of an atom, you add the mass of the protons and the neutrons. This is the nucleus of the atom. The electrons are small enough to be ignored except in the most delicate calculations.
Over 99% of the mass of an atom is contained in the nucleus, where protons and neutrons are located. Electrons, which have negligible mass compared to protons and neutrons, occupy the remaining space in the electron cloud surrounding the nucleus.
nucleus
An atom's mass is concentrated in its nucleus, which is located in the center of the atom. Protons and neutrons within the nucleus are responsible for its mass; the electrons, which are located outside of the nucleus, don't contribute to the mass of the atom.
Explanation: Neutrons are non charged particles in nucleus. They are present in order to reduce the repulsive forces between two or more positively charged protons, which are also present in the nucleus.
The difference is the number of neutrons contained in the atom's nucleus