Question

What is the isotope symbol for oxygen-18?

Answer 1

`""_8^(18) "O"`

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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 `"O"`, so knowing that there are `8` protons, the atomic number is...

`Z = 8`

and the mass number is...

`A = Z + 10 = 18`

Therefore:

`=> color(blue)(""_8^(18) "O")`