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The atom of an element has 2 electrons i...

The atom of an element has 2 electrons in the M-shell. What will be the atomic number of the element? Name the element.

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As the atom has 2 electrons in the M-shell, this means that K and L-shells are completely filled. As completely filled K-shell has 2 electrons and completely filled L-shell has 8 electrons, therefore, complete electronic configuration of the atom of the element will be
`{:(K,L,M),(2,8,2):}`
` therefore` Total number of electrons = 2 + 8 + 2 = 12
As the atom is neutral, total number of protons = total number of electrons = atomic number = 12. Hence, the element is magnesium.
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