Question

Which of the following is not a one-electron atom
A) H
B) He+
C) Li2+
D) Be2+
E) O7+
I know that H, He+, Li2+ and Be3+ are. i can't seem to find out about Be2+ and O7+. How do I calculate it?

Answer 1

Look at the periodic table. Be is atomic number 4 meaning it has 4 protons and 4 electrons for the neutral atom. Take away two electrons to make it +2 ion leaves 2 electrons.
O is atomic number 8. It has 8 protons and 8 electrons. Take away 7 electrons and that leaves ?? electron.

Answer 2

Thanks! That was what I thought.