question_answer 18)

An atom has electronic configuration 2, 8, 7. (a) What is the atomic number of this element ? (b) To which of the following elements would it be chemically similar? (Atomic numbers are giving in parentheses).                                  N(7),    F(9),    P(15),    Ar(18)

Answer:

(a)The atomic number of the element is 17 (2 + 8 + 7 = 17). (b) It will be chemically similar with fluorine (F) which has also 7 electrons in valence shell (2, 7).