Which corner of the isotope symbol contains the mass number?

1 Answer
Sep 29, 2016

The top left corner, as we read the symbol on the page.

Explanation:

When we write ""^12""_6C, the bottom left symbol is the atomic number Z; the top left smbol is the mass number. Since the elemental symbol, the C, automatically specifies the atomic number Z=6, it is redundant, and may be discarded to give just ""^12C. Reading this symbol, this tells us that we deal with a nucleon with 6 neutrons in the nucleus, 6 massive, neutrally charged, nucular particles.

For the ""^13C and ""^14C isotopes, how many neutrons in each such atom? And how many electrons? Why?