The electron that is transferred to form the Li+ ion comes from the 2s orbital of the lithium atom.

Here's why:

* Electronic configuration of Lithium: Lithium has an atomic number of 3, meaning it has 3 electrons. Its electronic configuration is 1s² 2s¹. This means it has 2 electrons in the 1s orbital and 1 electron in the 2s orbital.

* Ionization: When lithium loses an electron to become Li+, it loses the electron from its outermost shell, which is the 2s orbital. This leaves it with a full 1s² configuration, making it more stable.