Question

An atom with electrinic configuration 2,7 and mass number 19 will have _ neutrons

Answer 1

Answer:

The element is flourine and it has 9 neutrons

Explanation:

Answer 2

Answer:

10 neutrons

Explanation:

Electronic configuration is 2,7.

Hence no of electrons= 2+7= 9

Since an atom is stable,

No of electrons= No of proton = 9

We know,

Mass number= no of protons + no of neutrons.

Or ,no of neutrons = Mass number- no of proton.

Or, no of neutron = 19-9= 10.