Proton medical equipment precision instrument

A, the relative atomic mass can't be "g", so item A is wrong.

B, titanium ion Ti3+ contains 19 electrons instead of 25 electrons, so item b is also wrong;

C, the number in the upper left corner of each square in the periodic table indicates the number of protons, and there are 22 protons in the titanium core. C is correct.

D, titanium is a kind of metal chemical formula that can only be expressed by element symbols, so item D is also wrong.

So choose C.