Question

An element X forms a positive ion X* with
the electronic structure 2, 8, 8, 1. What is the
atomic number of X?
a) 16
b) 17
c) 20
d) 19​

Answer 1

$\huge{\star}{\underline{\boxed{\red{\sf{Answer :}}}}}{\star}$

X is Potassium

(d) And its atomic number is 19.

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More information

• Potassium is a 1st group metal.

• Potassium contains 1 electron In outermost shell so it shows proper of 1st group element.

• It donate its 1 electron to attain noble gas configuration which is Na+ .

• Electronic Configuration of Potassium = 2,8,8,1 or 1s²2s²2p6 3s²3p6 4s¹

• it's valency is 1