00:02
Hi there.
00:03
In these questions, we are given the isotopic notation for four different neutral atoms.
00:10
So when we have isotopic notation, x is going to represent the symbol of the element.
00:19
The number as a superscript before it is the mass number.
00:24
And the number that's a subscript before it is the atomic number.
00:29
All right, so the atomic number, of course, identifies the element.
00:33
We can find the element on the periodic table by its atomic number.
00:40
But what the atomic number also tells us is the number of protons.
00:50
All right, mass number is defined as the sum of the number of protons plus the number of neutrons in the nucleus.
01:06
All right, so that's going to be protons plus neutrons.
01:10
So we can find neutrons from that information.
01:14
Electrons, since we have a neutral atom, in neutral atoms, to be neutral, the number of protons, which are positively charged, must equal the number of electrons, which are negatively charged.
01:35
Okay, so we have a way to determine the number of protons, neutrons, and electrons.
01:39
Let's go ahead and get started.
01:41
Our first one is sodium.
01:44
It has an atomic number of 11 and a mass number of 24.
01:49
So i'm just going to set this up as a little table here.
01:52
We have protons, we have the number of neutrons, and we have the number of electrons.
01:59
Well since the atomic number is 11, the number of protons are 11...