Carbon-12 has 6 protons and 6 neutrons. When it gives up a proton, it has 5 protons and 6 neutrons. The element with atomic number 5 is boron. Boron is one of the elements near the top of the Nuclear Table. You can also determine that it's boron by looking at the Element Tables, which has a list of elements in order of atomic number.

Boron with 6 neutrons has mass number 11 (5 + 6), so the nucleus is ¹¹₅B.

The nucleus which receives the proton is the neon isotope with 10 protons and 11 neutrons. It becomes a nucleus with 11 protons and 11 neutrons. This nucleus is not in the Nuclear Table; you find it in the Element Table. The element with atomic number 11 is sodium (Na), and this isotope has mass number 22 (11 + 11). It is sodium-22.