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An example is calcium-40, with 20 neutrons and 20 protons, which is the heaviest stable isotope made of the same number of protons and neutrons. Both calcium-48 and nickel-48 are doubly magic because calcium-48 has 20 protons and 28 neutrons while nickel-48 has 28 protons and 20 neutrons. Calcium-48 is very neutron-rich for such a relatively ...
N 2 3 8 O 2 4 9 F 2 5 10 Ne 2 6 [Ne] 3s: 3p: 11 Na 1 - 12 Mg 2 - 13 Al 2 1 14 Si 2 2 15 P 2 3 16 S 2 4 17 Cl 2 5 18 Ar 2 6 [Ar] 4s: 3d: 4p: 19 K 1-- 20 Ca 2-- 21 Sc 2 1 - 22 Ti 2 2 - 23 V 2 3 - 24 Cr 1 5 - 25 Mn 2 5 - 26 Fe 2 6 - 27 Co 2 7 - 28 Ni 2 8 - 29 Cu 1 10 - 30 Zn 2 10 - 31 Ga 2 10 1 32 Ge 2 10 2 33 As 2 10 3 34 Se 2 10 4 35 Br 2 10 5 ...
The electrons are negatively charged, and this opposing charge is what binds them to the nucleus. If the numbers of protons and electrons are equal, as they normally are, then the atom is electrically neutral as a whole. If an atom has more electrons than protons, then it has an overall negative charge and is called a negative ion (or anion ...
For ordinary nuclei composed of protons and neutrons, this is equal to the proton number (n p) or the number of protons found in the nucleus of every atom of that element. The atomic number can be used to uniquely identify ordinary chemical elements. In an ordinary uncharged atom, the atomic number is also equal to the number of electrons.
Here [Ne] refers to the core electrons which are the same as for the element neon (Ne), the last noble gas before phosphorus in the periodic table. The valence electrons (here 3s 2 3p 3) are written explicitly for all atoms. Electron configurations of elements beyond hassium (element 108) have never been measured; predictions are used below.
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 is a list of chemical elements and their atomic properties, ordered by atomic number (Z).. Since valence electrons are not clearly defined for the d-block and f-block elements, there not being a clear point at which further ionisation becomes unprofitable, a purely formal definition as number of electrons in the outermost shell has been used.
For instance, in iron (atomic number 26), the nucleus contains 26 protons. The electrons that are closest to the nucleus will 'see' nearly all of them. However, electrons further away are screened from the nucleus by other electrons in between, and feel less electrostatic interaction as a result.