So let's take a look at condensed electron configurations. With condensed electron configurations, we start at the last noble gas, before the desired element. In this question it says, write the condensed electron configuration for the following element. Here we have to write the condensed electron configuration of calcium. Here we're given an atomic number of 20 which would mean in terms of our periodic table, calcium would fall here. The last noble gas that I pass before I get to calcium is argon. Remember, our noble gases are in group 8. So here our condensed electron configuration would start out with argon. Then we just have to count to calcium. Calcium is in the 4s row and then it's in slot 2. So that'd be argon 4s². Condensed electron configurations are huge time savers when it comes to electron configuration in general.

That's because if I wanted to write the full ground state electron configuration of calcium, I'd have to start out with 1s and count all the way to calcium. What would that look like? Well, that would mean that I'd have 1s²2s²2p⁶, 3s², 3p⁶ and then 4s². All of this here can be greatly shortened by just substituting in argon. It means the same exact thing. Again, when it comes to the full ground state electron configuration, only give that if they're asking for it specifically. Most of the time when it comes to electron configurations, we're writing them in the condensed form because again, it saves a lot of time.

Now that you've seen these 2 different types of electron configurations, click on to the 3rd video to take a look at our charged electron configurations and the rules that are applied when it comes to the electron configurations of these types of ions.