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Lithium atom. A lithium atom is an atom of the chemical element lithium.Stable lithium is composed of three electrons bound by the electromagnetic force to a nucleus containing three protons along with either three or four neutrons, depending on the isotope, held together by the strong force.
Naturally occurring lithium (3 Li) is composed of two stable isotopes, lithium-6 (6 Li) and lithium-7 (7 Li), with the latter being far more abundant on Earth. Both of the natural isotopes have an unexpectedly low nuclear binding energy per nucleon (5 332.3312(3) keV for 6 Li and 5 606.4401(6) keV for 7 Li) when compared with the adjacent lighter and heavier elements, helium (7 073.9156(4) keV ...
Conversely, if it has more protons than electrons, it has a positive charge and is called a positive ion (or cation). The electrons of an atom are attracted to the protons in an atomic nucleus by the electromagnetic force. The protons and neutrons in the nucleus are attracted to each other by the nuclear force. This force is usually stronger ...
Protons define the entire charge of a nucleus, and hence its chemical identity. Neutrons are electrically neutral, but contribute to the mass of a nucleus to nearly the same extent as the protons. Neutrons can explain the phenomenon of isotopes (same atomic number with different atomic mass). The main role of neutrons is to reduce electrostatic ...
Finally, there is a very low density of baryons (neutrons and protons). The BBN model follows the nuclear reactions of these baryons as the temperature and pressure drops due to expansion of the universe. [3]: 62 The basic model makes two simplifying assumptions: until the temperature drops below 0.1 MeV only neutrons and protons are stable and
Since protons and neutrons have approximately the same mass (and the mass of the electrons is negligible for many purposes) and the mass defect of the nucleon binding is always small compared to the nucleon mass, the atomic mass of any atom, when expressed in daltons (making a quantity called the "relative isotopic mass"), is within 1% of the ...
The 6 Li isotope is one of only five stable nuclides to have both an odd number of protons and an odd number of neutrons, the other four stable odd-odd nuclides being hydrogen-2, boron-10, nitrogen-14, and tantalum-180m. [27] 7 Li is one of the primordial elements (or, more properly, primordial nuclides) produced in Big Bang nucleosynthesis.
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.