If you add a proton to a lithium atom (3 protons, 4 neutrons, 3 electrons), you would no longer have a lithium atom. Here's why:

* Atomic Number: The number of protons defines the element. Lithium has an atomic number of 3. Adding a proton changes the atomic number to 4.

* New Element: An element with 4 protons is beryllium (Be).

So, adding a proton to lithium would create a beryllium atom. However, it's important to note that this is a very simplified explanation. In reality, changing the number of protons within an atom is a nuclear process that requires significant energy and usually results in radioactive isotopes.