Tutor hotline, Melissa Maribel, how can I help you? I had a quick question on
number 10, how many inner, outer, valence electrons are present in an atom of
Manganese? My question was how do you figure out how many inner and outer
electrons are present in an atom? Thanks. So the first thing we want to do for this
question is to figure out the electron configuration. So let's review how to
figure out the electron configuration specifically in this case for Manganese.
Alright, so what I'm going to start off with is just identifying where manganese
is on our periodic table and then where we'll find it as it's right here so I'm
gonna go ahead and circle that and we know that that's that's the goal that's
what we're trying to get up to for our electron configuration. So let's just
circle this is where we're trying to get to and then next for electron
configuration we're gonna start off with just writing the expanded electron
configuration and then I'm going to go over how to figure out the abbreviated
method that's just using the noble gas before it. So starting with just the
beginning, remember that this is our s block,
this is our p block and then in the center here this is our d block that's
all we really care about we're not going up until the f block right now. So I'm
going to start off at the very beginning and we always start at the very
beginning which is hydrogen. Okay so we're gonna start off with this is 1s
because this is in the first row and this is 1s1 and two because
there's two elements in that first row so we'll start writing that out. So this
is this is going to be 1s2. I'm going to continue so continuing from
here I make my way around now I'm on the second row and this is now 2s2 because
1 and 2 we're at beryllium now and we're gonna keep trying to just go all the way to
manganese. So now we add to 2s2 so I'm gonna write that 2s2. Continuing
from that point I'm going to go all the way across and then now we're still in
the second row but now we're in the p-block
so this is 2 p 1, 2 ,3, 4, 5, 6
so I'll write that 2p6 okay so we left off here I'm gonna keep going now I'm at
the third row and this is 3 s 1, 2 so 3s2, continuing from that point I'm going
to make my way across again I'm still in the same row in the third row and then
this is going to be 3p 1, 2, 3, 4, 5, 6 so I'll write this is 3p6.
We're gonna keep going okay so we're almost there so now I'm going to keep
going all the way to the fourth row we're in the fourth row this is now 4 s 1 and 2
so this is 4s2. For the d-block beware of this part, looking at the
d-block this you would think that it's going to be 4 d but for the d block it's
always one less, the coefficient is always 1 less than the row it's in. So
this is actually going to be 3d instead of 4d so now I'm just going to start
here and I'm gonna count and up until I get to the element that we want which is
manganese so this is 3 d 1, 2, 3, 4, 5 so that would have given us 3d5. Okay so
that is the complete or the expanded electron configuration now if I wanted
to figure out the abbreviated method at which I do recommend doing so I
recommend writing both out for this type of question so the abbreviated method it
involves the noble gas that comes right before that element that you're looking
for okay so it's literally in the row before it. So the noble gas that is
before manganese in the row before it which is in the third row is argon. So
what I'm going to do is I'm gonna put argon in brackets you always put the
noble gas in brackets and then I'm going to continue from argon and then I'm
going to go back so now we're at the fourth row we said that this was 4s2
so that's what I'm gonna continue writing after argon and then lastly we
said that we got 3d5 because we counted up until we got to manganese in
the d-block so this is going to be 3d5. Okay so now that we have that let's
continue on so we said we found our overall expanded electron configuration
and the abbreviated and yes I do recommend writing both out for this type
of question. The next thing we're gonna see the reason why this I love doing the
electron configuration in the beginning and the abbreviated is because it makes
it so much easier to figure out how many inner electrons outer electrons and
valence electrons just by looking at the electron configuration. So for the inner
electrons your inner electrons are always going to be pretty much just like
the electrons of your previous noble gas so we said our noble gas was argon and
then if we looked at the expanded electric configuration you could either
count up how many electrons we have and by the way these these little numbers up
here these exponents are really just talking about how many electrons are in
that shell so if we can if we were to add everything up like this is 6 plus 2
plus 6 plus 2 plus 2 that would give us 18 or we can just look at the atomic
number of argon which is also 18 and then that would give us how many inner
electrons that is so like I said the inner electrons are just the atomic
number of that noble gas. So we said okay there are 18 inner electrons so that's
the first part. Now let's continue to the second part of this which is the outer
electrons so for the electron configuration part what I'm looking at
for the outer electrons these are the electrons in the highest energy
levels and all that means is we're going to be looking at the coefficients in
front here and seeing which one has the largest coefficient which one has the
highest coefficient so in this case like by coefficient I just mean the number
in front so like 1,2, 2, 3 , 3 and 4 so out of all of these 4 is the largest one so
now I'm going to look at how many electrons are in that shell and I know
that there's 2 so in that case I see okay the outer electrons we only have 2.
Okay so that's always the case when we're looking at outer electrons and
then for valence electrons what we're going
to see and this is why I wrote the abbreviated method okay this is why I
wrote that here for the valence electrons it's going to actually be the last part
of the condensed electron configuration or abbreviated electron configuration so
it's just everything in this box so how much is that well that's going to be
remember our electrons are the exponents so that's two plus the five so that's
going to be 7 valence electrons just to reiterate our inner electrons are 18
our outer electrons are 2 and our valence electrons are 7 and as we
discussed this is where every little part of it came from it all came from
just knowing the electron configuration. If you want to get your questions
answered just like Jay did then all you have to do is submit your question by
using the link in the description box, if you need additional help with let's say
electron configuration here's the video for that and if you have any more
questions, if you need it tutoring, homework help, all of the links are going
to be in the description box along with so many more resources so make sure to
check that out and I'll see you next time.