What are the atomic numbers of elements whose outermost electrons… - Vidyadip

Question

What are the atomic numbers of elements whose outermost electrons are represented by

$3s^1$
$2p^3$
$3p^5$

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Answer

$3s^1$

Completing the electron configuration of the element as
$1s^2 2s^2 2p^6 3s^1.$
$\therefore$ Number of electrons present in the atom of the element
$= 2 + 2 + 6 + 1 = 11$
$\therefore$ Atomic number of the element $= 11$

$2p^3$

Completing the electron configuration of the element as
$1s^2 2s^2 2p^3.$
$\therefore$ Number of electrons present in the atom of the element $= 2 + 2 + 3 = 7$
$\therefore$ Atomic number of the element $= 7$

$3p^5$

Completing the electron configuration of the element as
$1s^2 2s^2 2p^6 3s^2 3p^51s^2 2s^2 2p^6 3s^2 3p^5$
$\therefore$ Number of electrons present in the atom of the element $= 2 + 2 + 6+2+5 = 17$
$\therefore$ Atomic number of the element $= 17$

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