A sample of fluorine contains isotopes with different masses; F-19 and F-18. In the sample 94% of the atoms are F-19. Calculate the relative mass of the sample.

The relative mass of the sample : 18.94

The elements in nature have several types of isotopes

Isotopes are atoms whose no-atom has the same number of protons while still having a different number of neutrons.

So Isotopes are elements that have the same Atomic Number (Proton)

Atomic mass is the average atomic mass of all its isotopes

Mass atom X = mass isotope 1 . % + mass isotope 2.%

F-19 = 94% of the sample

F-18 = 100%-94%=6% of the sample

The relative mass :