Main Isotopes

I read in the OCR AS level book that some, but not all elements have a main isotope. How do you know which one is the main isotope, and how do you know when an element doesn't have a main isotope? :confused:

Reply 1

thelostchild

10

Well obviously the ones with a fractional RAM on the periodic table do (eg Cl, Cu etc.) Other than that I guess its a case of learning sorry :smile:

Reply 2

~*starlight*conquest*~

OP

11

So it's not a case of abundance?

Reply 3

-Kav-

12

~*starlight*conquest*~

So it's not a case of abundance?

The RAM reflects the abundance. It comes from the average mass of the atom so, given that a single atom will always have an (approximately) integer mass, you'd need a considerable abundance of two isotopes to get an obviously non-integer value.

Reply 4

thelostchild

10

-Kav-

The RAM reflects the abundance. It comes from the average mass of the atom so, given that a single atom will always have an (approximately) integer mass, you'd need a considerable abundance of two isotopes to get an obviously non-integer value.