# Need help with isotopes: Chemistry!

#### ReoFonzo

1. Homework Statement

Sulfur has 4 naturally occurring isotopes:

Sulfur-32 Abundance = 95.0%
Sulfur-33 Abundance = 0.76%
Sulfur-34 Abundance = 4.22%
Sulfur-36 Abundance = 0.014%

Sulfur's symbol is S, it has 16 electrons and a mass of 32.06g

2. Homework Equations
I'm actually looking for the actual formula which I lost.

3. The Attempt at a Solution
Sulfur's Isotopes divided by its abundance...

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#### cristo

Staff Emeritus
What's the actual question here? What formula are you looking for?

Last edited:

#### ReoFonzo

how do i find calculate the average atomic mass for sulfur?

#### cristo

Staff Emeritus
Well, would you not take the sum of (mass of isotope*abundance of isotope) then divide the sum by 100?

#### vezina

m = mass of specified isotope
a = abundance of specified isotope as a part of 1.00 (100%

(m-32 x a-32) + (m-33 x a-33)... etc.

so (32.06 x .95) for sulfur-32 and so on