# Form the oxides of the element Z=39

Its electronic configuration is $4d^15s^2$ so in normal state it has valence=1 and in energetic state, valence=2 (because our teacher said we count only the electrons in the outer shell firstly) and valence =3. First question: is it true what my teacher said? It was for Z=22 example, where she said it has the valence 2 and 4). Second question when we form the oxide we should use only the valence in the energetic states and not the one in the normal state?

• No one looks at the periodic table through the lens of Z. This assignment is ... dumb. – Abel Friedman Dec 3 '14 at 18:36
• Z=38 is Sr, isn't it, and the electronic configuration is 4d0 5s2. – Abel Friedman Dec 3 '14 at 18:39