00:01
So for this question, we're told, the oxygen has three naturally occurring isotopes, 16, 17, and 18.
00:08
And that the atomic mass of oxygen is 16 amu or atomic mass units.
00:19
So this is from the periodic table.
00:22
And remember, atomic mass units, the 16, is calculated from an average of all the weights of each of the isotope.
00:35
In nature.
00:38
So what can we conclude, given that the average of all three isotopes is 16? well, if you think about it, i like to think about it on a number line.
00:54
If we had the same amount of each, right, a third of the oxygen, it was 16, a third of the oxygen was 17.
01:03
And what the oxygen was 18, if we averaged those all together, then its atomic mass would be 17, right? if we took all the averages of equal number of each one, it would be right in the middle at 17.
01:18
But it's 16, so that can't be true...