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!