What is Hund’s rule?

Hund’s rule is about how tiny particles called electrons choose their spots inside atoms, kind of like choosing seats on a bus.

Imagine you're getting ready for a fun ride with your friends, and there are two empty seats next to each other. You’d probably want to sit in one seat, and your friend would take the other, not both trying to squeeze into one seat. That way, everyone is more comfortable and has space to move around.

That’s exactly what Hund’s rule says: when electrons are filling up spaces inside atoms (which we call orbitals), they like to spread out as much as possible, each taking their own spot before sharing with another electron. This makes the atom more stable, just like you and your friend being happier with separate seats.

Think of it like a game where everyone gets a turn to sit in their own seat first, that’s fair! Only when all the seats are taken do electrons start pairing up. So, electrons prefer individual spots before they start sharing, just like you and your friends on the bus.