One isotope of a nonmetallic element has mass number 16 and 7 neutrons in the nucleus. The anion derived from the isotope has 10 electrons. Write the symbol for this anion.

Question

I thought the answer was O^2- but this isnt correct

Answer 1

mass # = #p + #n
16 = #p + 7
p = 9
So it must have 9 electrons so the charge must be -1 when the anion is formed.
9F^16. 9 is the subscript; 16 is the superscript and goes at the top left.