Final answer:
The element whose ion only exists as 1+ is lithium. Lithium is an alkali metal in Group 1 of the periodic table.
Step-by-step explanation:
The element whose ion only exists as 1+ is lithium. Lithium is an alkali metal in Group 1 of the periodic table. When lithium forms an ion, it loses one electron and becomes positively charged with an atomic number of 3 and a charge of 1+.