i have a homework question about the electronic configuration and valence electronic configuration of Sn4+. I know that electronic configuration of Sn and Sn4+ is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p2 and 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 4d10. So valence electronic configuration of Sn is 5s2 5p2, but what is the valence electronic configuration for Sn4+？ because the electron at n=5 is removed. In addition, what is the valence shell for Sn4+. I am so confused about this, thank you very much!!