Question

Use the information for the isotopes of X to calculate the average atomic mass of X, and identify the element.

Isotope Abundance Mass (amu)
6X 7.5% 6.015
7X 92.5% 7.016

I'm kinda confused :/

Answer 1

\(Average ~atomic~ mass~ of~ an ~element\)
=
\(
(Abundance~percentage_1*Mass~of~Isotope~ 1)\)
+
\((Abundance~percentage_2*Mass~of~Isotope~ 2))\)

Answer 2

So would I have to calculate that like 7.5 * 6.015, and the same for the other one?

Answer 3

You would add the two masses together

Answer 4

Correct. You'll add it with Isotope 7x to get the average atomic mass of the element

Answer 5

but first you need to multiply the atomic mass by the % abundance I believe

Answer 6

So it's 45.1125 + 648.98 ?

Answer 7

@Photon336 would it be 694.0925?

Answer 8

@Zale101 6X and 7X are just the names of the isotopes right?

Answer 9

I believe so.

Answer 10

Yeah they are...

Answer 11

yeah.. so convert 7.5% to decimal form which is 7.5/100 then you multiply this by 6.015 amu

Answer 12

remember @flatouthero its' a percentage

Answer 13

Oh, so it's 6.94

Answer 14

Correct!

Answer 15

:)

Answer 16

What element is that?

Answer 17

Thank you both for your help!

Answer 18

no problem

Answer 19

Lithium, btw xD