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# Electron configurations for the second period

Writes out quantum numbers for all elements of the second period. Introduces Hund's rule, and connects blocks in periodic table with electron configuration. Created by Jay.

## Want to join the conversation?

• What is a "ground state condensed electron configuration" for an element? Do we use the most recent/previous noble gas and simplify the configuration accordingly?
• Ground state - most stable, all electrons are in their natural state
Condensed - use closest noble gas with a smaller atomic number (so you're correct)
For example, calcium's ground state condensed electron configuration would be [Ar]4s^2
• Why do opposite spins of electrons in same orbital make it more stable?
• Electrons have charge, and a spinning charge generates an magnetic field. If you do the right hand rule, you'll see that electrons with opposite spins have opposing magnetic fields. Essentially, these magnetic fields "cancel" each other out, thereby making it more stable than if electrons were spinning in the same direction. The magnetic force would push electrons away from each other when electrons have the same spin.
• How would one state Hund's rule in a phrase?
• If two or more orbitals of equal energy are available, electrons will occupy them singly before filling them in pairs.
• If there's only one electron in an orbital, do we assume the spin is +1/2? Does it matter?
• It doesn't really matter.
It is just a convention to assign +½ to the first electron in an orbital.
• i suddenly feel like the hunds ruls as described in the videos suddenly contradicting what we have learnt before !
why its being said that there wecan only be one electron in px orbital when the previously learnt rule was that we cud accommodate 2 electrons in each orbital.
• Hund’s rule states that we fill electrons singularly into the orbitals of the same subshell before we begin pairing them.

For an s subshell this doesn’t affect the filling at all since there is only one orbital in an s subshell. For a p subshell however, there are three orbitals now. So using Hund’s rule we have to fill those three p orbitals with three electrons of the same spin before be begin spin pairing with the fourth electron.

Hope that helps.
• Does Hund's Rule apply only to p orbital or all the upcoming ones too like d ,f , etc?
• Hund's rule applies to all of the orbitals. 1 electron occupies each orbital, and only after all of the orbitals are filled does the orbital get filled with two electrons.
• Not sure if this question is answered, but Be has config 1s2,2s2, though it is not a Noble gs it is very tempting to say that it has filled subshells.Why we don't call it a complete octet or rather filled subshell
• So neutral beryllium does have a completed 2s subshell and gains a certain level of stability from this. We can tell this because beryllium has a noticeably higher first ionization energy compared to both lithium and boron. It is just that this level of stability isn't had pronounced as an actual noble gas.

Hope that helps.
• Can we write Neon(1s^2 2s^2 2p^6) as [Be]2p^6 ?