00:02
In this question we are given what is known as isotopic notation for an element.
00:10
We are told that x is the element's symbol.
00:18
It is either a one or two letter symbol.
00:22
If it is one letter it is capitalized.
00:24
If it is two letters the first is capitalized but the second is lowercase.
00:28
We want to know about a and b.
00:31
Let me start with b.
00:33
B in the bottom left is a subscript before the element.
00:40
B is always going to be the atomic number.
00:46
The atomic number is the whole number on the periodic table.
00:52
But perhaps more importantly it tells us the number of protons in every atom of that type of element.
01:04
If it is sodium for example, sodium's atomic number is 11...