Question

an element has electronic configuration 2, 8, 5
what is its atomic number
write the group number and period to which this belongs to in the periodic table
to which of the following elements would it be chemically similar
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Answer 1

Answer:

(a)The atomic number of element with electronic configuration 2,8,7=17.

(b)It has 7 valence electrons, therefore it would be chemically similar to F(9)=2,7.