Lithium with symbol Li has an atomic number of 3.
First energy shell has s orbital and can hold up to 2 electrons. Second energy shell has s orbital and p orbital and altogether 2nd energy shell can hold upto 8 electrons.
Li electronic configuration is 1s^2 2s^1
Li has one electron in the outer shell, to become stable it loses that electron.
As Li loses one electron, its net charge becomes +1
electronic configuration of Li⁺ - 1s^2
