Question

Lithium is a metal whose electronic configuration is 2 and 1 including 3 protons 3 electrons and 3 neutrons. So, if we remove 1 electron from lithium to make it stable. Then ,why would we call it lithium as it has 3 protons 3 electrons and 3 neutrons. But , after removal of 1 electron only 2 electrons are left. So, why would we call it lithium then.

Answer 1

Lithium is the third element with a total of 3 electrons. In writing the electron configuration for lithium the first two electrons will go in the 1s orbital. Since 1s can only hold two electrons the remaining electron for Li goes in the 2s orbital. Therefore the Li electron configuration will be 1s²2s¹.

Now, the lithium cation, Li+, is formed when lithium loses the electron located on its outermost shell → its valence electron. This electron is located on the second energy level, in the 2s-orbital.

This means that the electron configuration of the Li+ cation will be

Li+:1s2

To write this using noble gas shorthand notation, use the electron configuration of the noble gas that comes before lithium in the periodic table.

Helium, He, has the electron configuration

He: 1s2

This means that you have

Li+:[He]

Here the notation [He] is meant to represent the electron configuration of helium.