# What is atomic concentration?

1. Jan 19, 2010

### y4ku24

Hello everyone.

Just a quick question: Could somebody explain to me what atomic concentration is, and whether there is a list of all the atomic concentration of the elements somewhere in the internet.

The 1st time I heard the term, I typed it on wikipedia and google, surprisingly the search did not come out with a straight answer of what it is. Is there another word for it?

2. Jan 19, 2010

### Mapes

The atomic concentration of X is the ratio of the number of atoms of X to the total number of atoms. The atomic concentration of any pure element is 100%.

3. Jan 19, 2010

### y4ku24

Dear Mapes,

Thank you for your feedback. However, I am reading a paper stating that a Fe90Zr10 alloy has an atomic concentration of Fe: 8.5x10^28 m^-3 and Zr: 4.29x10^28 m^-3

If it is a ratio, why is there a unit, and how did they come up with the estimated values above?

4. Jan 19, 2010

### Mapes

OK, this is also a way of reporting concentration. They're dividing the mass density (kg m-3) by the atomic weight (g mol-1) and multiplying by Avogadro's number (6.022 x 1023 atoms mol-1). Does this help?

5. Jan 19, 2010

### y4ku24

Yup, very much! thanks again.