Atomic Number Facts

Atomic Number Facts
The atomic number of an element refers to the number of protons found in the nucleus of one of its atoms. Since that number refers to the protons, it is the same as the charge number of the nucleus. If the atom is uncharged, the number is the same as the number of electrons.
Interesting Atomic Number Facts:
The atomic number is often wrongly confused with the atomic mass number, which refers to the number of protons and neutrons together in the nucleus.
The neutron number, or number of neutrons, when added to the atomic number, equals atomic mass number.
The protons and neutrons of an element's nucleus have essentially the same mass, so the atomic mass is often very close to the atomic number.
An isotope is a product of an element whose atom has a different neutron number than atomic number.
More than 75% of all elements on Earth are a mixture of their isotopes.
The periodic table of the elements, constructed by Russian scientist Dmitri Mendeleev, orders the elements by their atomic numbers.
They were originally ordered by their atomic weights, but after noting the different chemical properties of the elements, he restructured it to move tellurium before iodine.
Antonius van den Broek theorized in 1911, after Ernest Rutherford's incorrect assumption that atoms' nuclei accounted for half their atomic weight, that the number of electrons equaled the element's place in the periodic table.
Moseley went on to prove this theory using spectral lines in1913.
The discovery of the neutron nearly twenty years later helped solidify scientists' understanding of how atomic number correlates with elements' positions on the table.
A number of new elements were discovered simply due to the fact that an element was missing at a certain atomic number. This opened the door for research and discovery, by aligning new observations with the appropriate blank spots on the periodic table.

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