write reason for the following (number in parenthesis is atomic number of substance).
1.Lithium (3) and sodium (11) are considered as active metals.
2. fluorine(9) is more active than chlorine(17)
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 given in parentheses.)
N(7) F(9) P(15) Ar(18)
The atomic number of chlorine is 17. The total number of electrons in chlorine atom is ___.