##### rubidium has2 common isotopes, 85Rb and 87Rb if the abundance of 85Rbis 72,2%

 Chemistry Tutor: None Selected Time limit: 1 Day

and the abundanceof 87 Rb is27.8% what is the average atomic mass of rubidium?

Sep 25th, 2015

isotopes are atoms that have the same number of protons but different number of neutrons hence have different mass numbers.

to calculate the average atomic mass of an element, multiply the mass of each isotope by its natural abundance, expressed as a decimal and then add the products.

for example for the above question on rubidium, the average atomic mass is:

=(85*72.2/100) + (87*27.8/100)

=(85*0.722) +(87*0.278)

61.37+24.186

=85.556 amu

NB: the average atomic mass will always be close to the element with the highest percentage abandance

Please let me know if you need any clarification. I'm always happy to answer your questions. Kindly ask you to make me your tutor and you will be assured of best results
Sep 25th, 2015

...
Sep 25th, 2015
...
Sep 25th, 2015
Dec 9th, 2016
check_circle