Elements in group 1 and group 2 are metals. Atoms of group 1 elements have one electron in their outer shell, and atoms of group 2 elements have two electrons in their outer shell. Elements in ...

This work reports the design of an efficient multiband UC system based on Ln3+/Yb3+-doped core-shell upconversion ...

As we move down the column of Group 7 elements, their reactivity decreases. In each, the outer shell is further from the nucleus and the incoming electron is not as easily attracted to it.