Isotope notation is a standardized method for representing atoms, clearly indicating the element, the number of protons and neutrons in the nucleus, and the net electrical charge. This notation is crucial in nuclear chemistry for quickly understanding the composition of atomic nuclei.
Mind Map
Click to expand
Click to explore the full interactive mind map • Zoom, pan, and navigate
isotope notation isotope notation is a
way that we can write the symbol for an
atom and show the number of protons
neutrons and sometimes electrons that
are in it isotope notation you see it
all over chemistry but it's particularly
important in nuclear chemistry because
in nuclear chemistry it's all about the
nucleus and so when when we write down
an atom we want to be able to show
pretty quickly how many protons and
neutrons are in it
so here is what it looks like to write
an atom in isotope notation we got a
couple things going on here first we got
these letters the letters represent the
element of the atom that we're dealing
with so here it's mg so we know which
stands for magnesium so we know we're
talking about an atom of magnesium then
we got these numbers
here the number down here is the atomic
number it's the number of protons that
are in the nucleus of this atom so here
we have 12 protons in the nucleus an
atomic number of 12 the number up here
is called the mass number which is the
number of protons plus the number of
neutrons don't make the mistake and
think that this is the number of
neutrons because it's not it's protons
plus neutrons together then we've got
two plus here and this represents the
net charge of this atom so we've got
protons and electrons and they balance
each other out so we have the same
number of protons and electrons have a
net charge of zero but unless we have
the exact number the exact same number
of protons and electrons the atom is
going to have a charge that's a little
bit negative or a little bit positive
and that's what the net charge
represents when we write something in
isotope notation it's usually because we
want to be able to find out the number
of protons neutrons and I said sometimes
electrons if you're adding the net
charge in here let's do this
now how many protons are in this atom
okay that's easy the atomic number here
is 12 so 12 protons how many neutrons in
this in this atom okay that's a little
bit harder because we don't have a
number here that's actually neutrons but
this number here is protons plus
neutrons together so if I know protons
and neutrons and I know the number of
just protons I can take my protons and
neutrons my mass number and subtract the
atomic number subtract the number of
protons and I get 25 minus
12 going to give me 13 neutrons the mass
number minus the atomic number okay
finally electrons here's how I like to
think about it this is a net charge of
positive so it means that we have to
have more protons than electrons and
since it's 2+ it means we have to have
two more protons than electrons okay so
if we had 12 electrons these guys would
balance out and they'd be neutral since
I need to have two more protons and
electrons I want to take the balanced
number of electrons minus two is going
to give me 10 electrons now I have two
more protons and electrons and that's
going to give me a plus two net
charge Let's do let's do another example
here let's swap
in titanium now you'll see something
right away about titanium and that's
that titanium doesn't have a net charge
written here and so if you write an atom
you see an atom written in isotope
notation and it doesn't have a net
charge that mean if it doesn't have a
net charge written up here that means a
net charge is zero the protons and
electrons balance perfectly so protons
neutrons and electrons for this guy
protons is the atomic number
22 and neutrons the mass number 48
protons plus neutrons minus 22 the
number of protons
and we get 26
neutrons for electrons they balance out
with protons and as we said since
there's nothing nothing up there it has
a zero net charge so that means I've got
22 protons and I've got 22 electrons
okay so now I want to go in the other
direction instead of taking a symbol and
finding out the number of protons
neutrons and electrons I want to start
with protons neutrons electrons I
already know how how many I have and I
want to write this symbol here okay so
let's start out with the atomic number
15 number of protons
okay I'll write that in right here now
how about the mass number well the mass
number is protons plus neutrons so I'll take
take
15 add it with 17 and I'm going to get
32 so that's the number that goes up
here 32 for the mass number okay what's
the letter that goes here what's a
chemical symbol well in order to find
that out I have to look on the periodic
table and I want to look for the element
that has an atomic number of 15 if I do
that I find out here that it's
phosphorus because I've got this 15 up
here so that means that any atom that
has 15 protons in it has an atomic
number of 15 it's phosphorus okay so I
put a big p here that stands for
phosphorous and now the net charge
what's going on here I've got my
electrons and I got my protons in this
example I have more electrons than I
have protons which means that my net
charge is going to be negative I've got
three more electrons and protons so that
means that the net charge is going to be
3 minus I kind of like to just figure it
out you know think about how many more
electrons or protons I have but if you
want to know how to always calculate the
net charge you can take the number of
protons and subtract the number of
electrons from it and there I get -3 and
that's my net charge we usually write
things 3 minus when we're doing the net
charge two minus you know that kind of
thing let's do another one of these okay
so what's the symbol of this going to be
it's always best to start with the
atomic number because that's really
straightforward 18 18 protons in the
nucleus now how about the mass number
I'm going to do protons plus neutrons 18
+ 22 is going to give me 40 so the 40
goes up here how about the symbol the
symbol uh is dependent on this number
here 18 and look on the periodic table
to find out the atom that has an atomic
number of 18 and that's argon right here
so a is a symbol there how about the net
charge how do the protons and electrons
balance out it turns out that I have 18
protons and 18 electrons so they balance
out perfectly meaning that my net charge is
is
zero I just leave it blank I don't write
anything in there and that tells me that
I I don't have a net charge there okay
so that's how we can take an atom
written in isotope notation and figure
out the number of protons neutrons and
electrons that it has in it and then we
can also do the opposite we can take a
given number of protons neutrons and
electrons and go ahead and write the
symbol for it so that that is that's
Click on any text or timestamp to jump to that moment in the video
Share:
Most transcripts ready in under 5 seconds
One-Click Copy125+ LanguagesSearch ContentJump to Timestamps
Paste YouTube URL
Enter any YouTube video link to get the full transcript
Transcript Extraction Form
Most transcripts ready in under 5 seconds
Get Our Chrome Extension
Get transcripts instantly without leaving YouTube. Install our Chrome extension for one-click access to any video's transcript directly on the watch page.
