Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: A sodium (Na) atom contains 11 protons, 12 neutrons, and 11 electrons. In order to make the sodium ion Na+, what must occur to the sodium atom?
Loss of one electron.