1. Radium has 88 protons. 2. Radium has not... americium !
All isotopes of radium have the same number of protons; the number of neutrons is different.
88
Radium has 88 protons.
The number of protons of an atom is given by its atomic number. Checking the periodic table, we see that the atom with 88 protons is radium. The isotope of radium with 138 neutrons would thus be 226Ra.
Radium has 88 protons, radon has only 86 protons.
Radium is a none metal element. atomic number of it is 88.
Radium has 88 protons. The atomic mass of the most stable radium isotope - 226Ra - is 226,025 409 8(25).
The neutrons aren't really relevant, since we don't know what the mass of the radium nucleus was and the element is determined strictly by the number of protons anyway. Radium has an atomic number of 88; losing 4 protons would make the atomic number 84, which is polonium. (This is probably really a two-step process: radium -> radon -> polonium, where each step is an alpha decay.)