Question

The atomic number of fluorine is 9. How many electrons does an ion of fluorine have if it is represented by the symbol shown below?

19F1-

A. 8 electrons
B. 9 electrons
C. 10 electrons
D. 20 electrons

Answer 1

• See charge on ion is -1 .

Hence it has taken 1 electron

Now first look at EC of Fluorine(F)

`\\ \bull\sf\dashrightarrow 1s^22s^22p^5`

• Now one electron added .hence no of electrons is 10now

Look at the EC

`\\ \bull\sf\dashrightarrow 1s^22s^22p^6`

Or

`\\ \bull\sf\dashrightarrow [He]`

Option C is correct.