Electrons in Orbitals

[Alen Huang 2G]

How come electrons fill up orbitals with an up spin instead of completely filling that orbital with an up and down spin before moving on? So like why do the last 2 electrons in a carbon atom occupy the 2px state and the 2py state instead of 2 electrons in the 2px state.

[Brianne Conway 1D]

I don't know why the first electron in an orbital is specifically spin-up, but I'm pretty sure they occupy different orbitals before filling them up because of the repulsion forces between them, so they'd want to be as far away as possible and thus occupy different orbitals.

[DanielHong2L]

I don't know why the first electron in an orbital is specifically spin-up, but I'm pretty sure they occupy different orbitals before filling them up because of the repulsion forces between them, so they'd want to be as far away as possible and thus occupy different orbitals.

Also spin-up / spin-down isn't really up nor down.

It's two different variations of electron behavior so there's no particular difference between up nor down except it's to describe that there exists two behaviors which adds further differentiation in electron state.

[Sofia Lombardo 2C]

According to Hund's Rule, electrons are added to degenerate (same energy) orbitals with a parallel spin (so either all facing up or all facing down) before pairing up. I think that this is a result of electron electron repulsion.

[SashaAnand2J]

Hi Alen!
Electrons like to fill up orbitals in order from lowest to highest energy, in terms of filling up s, p, d, f orbitals. This may be the same reason electrons fill up individual orbitals before completing pairs. Adding on to what Brianne said above, electrons are likely to take up locations that will prevent repulsion. By positioning in empty orbitals, electrons avoid these interactions with one another.

[Gustavo_Chavez_1K]

Honestly this is a really good question! It would make sense to just fill up an orbital before moving to the next, however electron's are all negatively charged. Since they are all negatively charged, electrons repel and want to stay far away from one another as possible. To do this, they fill up all the different orbitals before pairing with electrons already in an orbital. Hope this answers the question, if you want to read up on more of the specifics you should look into Hund's Rules.