Question

12 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?
N(7)
F(9) P(15)
P1151
Ar(180)
Arlen​

Answer 1

Answer:

a)answer is 17 b)F(9)

Explanation:

a)given its electronic configuration as 2,8,7.

so total number of electrons is 2+8+7 i.e;17

so its atomic number is 17(chlorine).

b)answer is F(9) because in groups; elements have similar physical and chemical properties this is because in elements ina group have same no.of electrons in outer most shell

chlorine and flourine are in same group.so they both have similiar chemical properties.

Answer 2

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(a)The element with electronic configuration (2+8+7) 17 is chlorine.

The no. of atomic number = no. of electrons

Therefore, atomic number is 17.

(b) An atom with electronic configuration 2, 8, 7 would be chemically similar to F (9)