Question

what will be the group number of element A having three electrons in its outermost shell??
most of the answers I received is 13 group why 3 group is not the answer???​​​​​

Answer 1

Element A of Group 13 will have three electrons in its outermost shell.

It can't be Group 3 because elements of Group 3 will have only two electrons in their outmost shell.

Example:

(i) Scandium ($Sc$): It is classified as a transition metal or rare earth metal. Scandium atoms have 21 electrons and 21 protons with 2 valence electrons in the outmost shell. Scandium adds one more electron to the outermost shell. Instead of having three electrons in the outer shell, scandium adds its electron to the second last shell (electric configuration is shown below).

(ii) Yttrium ($Y$): It have 39 electrons and 39 protons with 2 valence electrons in the outermost shell.  Instead of having three electrons in the outer shell, Yttrium adds its electron to the second last shell (electric configuration is shown below).

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