Photoelectric effect

Can anyone explain to me why in the gold leaf electroscope experiment the gold leaf gets attracted to the electroscope when electrons are emitted from the plate?

It isn't really attracted. Basically you use something eg a polythene rod and cloth to give the apparatus a negative charge first. The negative charge evenly distributes itself throughout the stem and gold leaf. Because they now have the same charge, they repel each other, which is what causes the gold leaf to rise. Now when you shine UV light onto the plate, and electrons are emmitted, the stem and gold leaf lose their negative charge so they are no longer repelling and the gold leaf falls back down. Hope this helps.

When electrons are emitted, the zinc plate loses its charge. The electroscope stem and leaf stay negative don't they?

No, they both become neutral because electrons are emmitted so they lose their negative charge. So the gold leaf falls back down.

but aren't electrons emmitted from the zinc on top not form the stem of the electroscope

Yeah, but the stem and gold leaf are connected to the zinc plate. Charge likes to evenly distribute itself. Remember that in metals the outer electrons are delocalised and can move around. so if electrons are lost from the plate, the rest of the electrons will move around to make the charge more even, making the plate, the stem and the gold leaf all neutral.

oh that makes sense. thanks. is there any chance that you could answer some of my other questions?

Welcome
you can definitely ask me, i'll help you if i can!