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Furthermore, the energy needed to excite the nucleus (i.e. moving a nucleon to a higher, previously unoccupied level) is exceptionally high in such nuclei. Whenever this unoccupied level is the next after a full shell, the only way to excite the nucleus is to raise one nucleon across the gap, thus spending a large amount of energy. Otherwise ...
The atomic nucleus is a bound system of protons and neutrons. The spatial extent and shape of the nucleus depend not only on the size and shape of discrete nucleons, but also on the distance between them (the inter-nucleon distance). (Other factors include spin, alignment, orbital motion, and the local nuclear environment (see EMC effect).)
The Voronoi cell of atom A is therefore the region of space closer to nucleus A than to any other nucleus. Furthermore, ρ ( r ) is the electron density of the molecule and Σ B ρ B ( r ) the superposition of atomic densities ρ B of a fictitious promolecule without chemical interactions that is associated with the situation in which all atoms ...
A model of an atomic nucleus showing it as a compact bundle of protons (red) and neutrons (blue), the two types of nucleons.In this diagram, protons and neutrons look like little balls stuck together, but an actual nucleus (as understood by modern nuclear physics) cannot be explained like this, but only by using quantum mechanics.
Sometimes there is a large gap between two yrast states. For example, the nucleus 95 Pd has a 21/2 state that lies below the lowest 19/2, 17/2, and 15/2 states. This state does not have enough energy to undergo strong particle decay, and because of the large spin difference, gamma decay from the 21/2 state to the 13/2 state below is very unlikely.
A table or chart of nuclides is a two-dimensional graph of isotopes of the elements, in which one axis represents the number of neutrons (symbol N) and the other represents the number of protons (atomic number, symbol Z) in the atomic nucleus. Each point plotted on the graph thus represents a nuclide of a known or hypothetical chemical element.
This means that the spin (i.e. angular momentum) of the nucleus, as well as its parity, are fully determined by that of the ninth neutron. This one is in the first (i.e. lowest energy) state of the 4th shell, which is a d-shell (ℓ = 2), and since p = (−1) ℓ, this gives the nucleus an overall parity
Inside a nucleus, on the other hand, combined protons and neutrons (nucleons) can be stable or unstable depending on the nuclide, or nuclear species. Inside some nuclides, a neutron can turn into a proton (producing other particles) as described above; the reverse can happen inside other nuclides, where a proton turns into a neutron (producing ...