We'll go over the two different ways to write the electron configuration but
don't worry I'll go over everything step by step. Hello everyone I'm Melissa Maribel
your personal tutor and here's what you really need to know for
electron configuration. Electron configuration helps us see how electrons
are arranged in atomic orbitals for a specific element. There are four types of
sub shells s, p, d and f the s subshell has one orbital that can hold up to two
electrons. The p subshell has three orbitals that can hold up to six
electrons. The d subshell has five orbitals that can hold up to 10
electrons and the f subshell has seven orbitals that can hold up to fourteen
electrons. The periodic table has all four types of subshells on it we refer
to it as a block. These first two groups are our s block and helium is also part of
the s block, on the opposite side is our p block, the inner transition metals are
our d block and finally at the bottom we have our f block.
Make sure you know these, this is the specific order that we follow for
electron configuration and yes the order does matter. Let's do an example of an
element in each block. Example 1: s block to find the electron configuration of
any element we always start from hydrogen and make our way going from
left to right to the element we are trying to find which in this case is
beryllium. So writing our electron configuration since we start with the
first row hydrogen is 1s1, we move on to helium which is 1s2 so we have 1s2.
Next we are on the second row but still in the s block so 2s1,2, 2 s2
and we stop since we reached the element we wanted. This is the electron
configuration of beryllium. Example 2: p block we'll find the electron
configuration of sulfur by starting from hydrogen and making our way to
sulfur. So 1s1, 2, 1 s2 is the first part, come back around on to the
second row 2s1, 2, 2 s2 is the second part, keep going straight across to the p
block, 2p, 1, 2, 3, 4, 5, 6, 2p6 is next, come back around onto the 3rd row to 3s1, 2
so 3s2, keep going straight across to the p block in row 3 and we will count
up until we get to sulfur so 3p, 1, 2, 3, 4, 3p4, this is our full electron
configuration for sulfur. There is an abbreviated, shorthand or condensed
electron configuration that you will need to know how to find. Let's find it
for sulfur, we always use the noble gas that is in the row before the element
we are looking for in this case it's neon and we place the noble gas in
brackets. Think of the noble gas as a placeholder or the new place to start so
we will continue after neon and write the remaining parts of the electron
configuration for sulfur. So 3s2 & 3p4, you know by placing our neon first we
are actually accounting for this entire portion of the full electron
configuration since that portion is the electron configuration of neon. Let's do
another example. Example 3: d block we'll find the electron configuration of iron
by starting from hydrogen and making our way to iron. So 1s2, 2s2,
keep going straight across to 2p6 come back around to 3s2, straight across to
3p6, come back around to the 4th row to 4s2. Now we are in the d
block and the coefficient or number in front is always 1 less than the row it
is in. So instead of 4d this is actually 3d and we will count up until we get to
iron so 3d, 1, 2, 3, 4, 5, 6, 3d6 this is our full electron configuration for iron.
Now let's find the condensed electron configuration using the noble gas in the
previous row which is argon we'll continue from argon to iron. Do 4s2 &
3d6 and this is our condensed electron configuration. Example 4: f block we'll
find the electron configuration of plutonium by starting from hydrogen and
making our way to plutonium so 1s2, 2s2 keep going straight across to 2p6, come
back around to the 3s2, straight across the 3p6, come around to the 4th row
to 4s2, remember the coefficient or number in front is always 1 number less
then the row it is in for the d block so we have 3d10. We're still in the
fourth row so 4p6 come around to the fifth row to 5s2 we're in the d block so
4d10, still in the fifth row to 5p6, come around to the sixth row to 6s2 and we
have a break in our periodic table, your clue is the change in atomic numbers we
are now in the f block which is at the bottom. Now the coefficient or number in
front is always two numbers less than the row it is in for the f block. So
instead of 6f we will write 4f and this is 4f14, now we go back up to the
d block we know this because the atomic numbers
have to go in order here we had an atomic number of 70 so next is 71, so 5d10
continue to 6p6, come around to the seventh row to 7s2. There is a break in
the table again to the f block so 5f,1, 2, 3 ,4, 5, 6 , 5f6. Here's the full electron
configuration. Now let's find the condensed electron configuration using
the noble gas that is before plutonium, so plutonium is at the bottom but would
have been in the seventh row so we will use the noble gas in the six row which
is radon and continue from there so 7s2 and 5f6 and here's the condensed
electron configuration. Now if you would like help with your homework online
tutoring or other helpful resources I have all of that and more in the
description box and if you want to make sure you're ready for your next exam
I created a practice quiz video just for you with of course step-by-step answers
you can find that right here and remember stay determined you can do this!