Wiktionary
n. (context physics English) A nucleus of an atom; consisting of protons and neutrons, surrounded by an electron cloud.
Wikipedia
The nucleus is the small, dense region consisting of protons and neutrons at the center of an atom. The atomic nucleus was discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment. After the discovery of the neutron in 1932, models for a nucleus composed of protons and neutrons were quickly developed by Dmitri Ivanenko and Werner Heisenberg. Almost all of the mass of an atom is located in the nucleus, with a very small contribution from the electron cloud. Protons and neutrons are bound together to form a nucleus by the nuclear force.
The diameter of the nucleus is in the range of for hydrogen (the diameter of a single proton) to about for the heaviest atoms, such as uranium. These dimensions are much smaller than the diameter of the atom itself (nucleus + electron cloud), by a factor of about 23,000 (uranium) to about 145,000 (hydrogen).
The branch of physics concerned with the study and understanding of the atomic nucleus, including its composition and the forces which bind it together, is called nuclear physics.
Usage examples of "atomic nucleus".
An atomic nucleus has a magnetic field that interacts with the field of the electrons.
No useful release of the energy locked up inside the atomic nucleus would ever be realized if every nuclear fission inside the uranium fuel required a neutron fired in from the outside to trigger it.
So FDR didnt really know the difference between a fissioning atomic nucleus and a disease organism, except that he could see that it was cheaper to culture germs in Petri dishes than to build billion-dollar factories to make this funny-sounding, what-do-you-call-it, nuclear explosive stuff, plutonium.
The plutonium atom has an atomic weight of 239, that being the combined number of neutrons and protons in the atomic nucleus.
Neutron: An uncharged particle, very similar to the proton, which accounts for roughly half the particles in an atomic nucleus.
The spontaneous breakdown of one type of atomic nucleus into another.
At the center of the atom, there was an atomic nucleus which carried a positive charge that balanced the negative charges of the circling electrons.
From Cambridge came an estimate for the minimum tensile strength of scrith: of the order of magnitude of the force that holds an atomic nucleus together.