When a lithium atom forms an li+ ion, the lithium atom
(1) gains a proton
(2) gains an electron
(3) loses a proton
(4) loses an electron

4, loses an electron. a plus sign indicates an atom is losing an electron while a minus sign indicates an atom is gaining an electron
hope this helps!

Both models are effective because they show the valence electrons, and these valence electrons indicate the reactivity of an element.

☆ionisation energy increases across a period from na -> ar☆ionisation energy decreases down a group from li -> fr☆ionic radius decreases across a period from na -> cl☆ionic radius increases down a groupfrom f -> ii hope it clarifies your doubts