00:04
If we look at the decay of phosphorus 32, we know it decays by beta decay.
00:10
And to figure out what the balanced equation would be, we first have to look at the atomic number of phosphorus.
00:18
So from the periodic table, we find the atomic number of phosphorus is 15.
00:24
We know it decays by beta decay.
00:28
So no mass is lost.
00:33
From the mask number, but our atomic number will actually increase by one.
00:41
And we know the mass number on the left has to equal the sum of the mass numbers on the right.
00:47
So 32 equals 0 plus 32.
00:51
And we know the sum of the atomic numbers on the left has to equal the sum of the atomic numbers on the right.
00:58
So 15 equals minus 1 plus 16.
01:03
Don't let that minus one fool you.
01:05
And looking on the periodic table, the element with atomic number 16 is sulfur.
01:11
So that is our final balanced equation.
01:15
Now, if we start with 4 .8 micrograms of phosphorus 32, and we want to know how much remains after 28 .6 days, first we have to know our half -life and our half -life.
01:34
Is half life is 14 .3 days.
01:46
Okay, then we take our total time that's passed 28 .6 days...