Question

help chemistry 6 . question

Answer 1

Okay!!! This question might look difficult, however it is actually pretty simple.

Let's start by listing out the information we were given.

Br-79   is 49.7%

Br-81    is 50.3%

These represent the different possible isotopes of bromine. Where the percentages show us what percent of that isotope makes up the total amount of bromine found in the world.

To find 49.7% of the total bromine, we multiply it by it's isotope, so:

49.7% x 79

= 3926.3

To find 50.3% of the total bromine, we multiply it by it's isotope, so:

50.3% x 81

= 4074.3

Add them together to make it 100%:

3926.3 + 4074.3

= 8000.6

Now, to find average atomic mass, we divide it by 100 to get 1 atom of bromine. (Right now it is at 100 atoms) :

8000.6 / 100

= 80.006

I hope this helped explain the concept of average atomic mass, and how scientists get that number to put on the periodic table. Let me know if there is anything I should work on when I explain, or what I did well.