The question reads: Place the following elements in order of decreasing atomic size: selenium, chlorine, fluorine, rubidium, calcium, and sulfur.
I looked this up on a periodic table and my answer was: Rb, Se, Ca, Cl, F, S.
This is still marked wrong, and I don't know why.
Size increases top to bottom and decreases left to right. Therefore, Rb is the largest and F is the smallest.
I would do this as
Rb, Ca, Se, S, Cl, F.posted by DrBob222
dfadfposted by Anonymous