What is the isotope symbol for oxygen-18?

May 20, 2017

$\text{_8^(18) "O}$

Recall:

""_Z^A X

where:

• $Z$ is the atomic number, i.e. the number of protons.
• $A$ is the mass number, the number of protons plus neutrons.
• $X$ is your chemical symbol.

We know that oxygen atom is $\text{O}$, so knowing that there are $8$ protons, the atomic number is...

$Z = 8$

and the mass number is...

$A = Z + 10 = 18$

Therefore:

$\implies \textcolor{b l u e}{\text{_8^(18) "O}}$