The mass of the most known and stable isotope of radium, 226Ra, is 226,025 409 8(25).
The atomic mass of the radium isotope 226Ra is 226,025 409 8(25).
88
The mass number of the isotope 228Ra is 228.
The density of radium at about room temperature is 5.5  g·cm−3. That's 5.5 grams per cubic centimeter, or 5.5 grams per milliliter. A link to the Wikipedia article on radium is provided.
Radium has 88 protons. The atomic mass of the most stable radium isotope - 226Ra - is 226,025 409 8(25).
The atomic mass of the most common isotope of radium (226Ra) is: 226,025 409 8(25).
The atomic mass of the radium isotope 226Ra is 226,025 409 8(25).
88
The most stable isotope of radium - 226Ra - has the atomic mass 226,025 409 8 (25).
The mass number of the isotope 228Ra is 228.
The density of radium at about room temperature is 5.5  g·cm−3. That's 5.5 grams per cubic centimeter, or 5.5 grams per milliliter. A link to the Wikipedia article on radium is provided.
The atomic number is 88 and the atomic mass is 226
When Radium-226 decays to form Radon-222, the Radium nucleus emits an alpha particle. The atomic number goes down by 2, and the mass number goes down by 4, matching the atomic number and mass number of the alpha particle.
Radium 226--------alpha particle-------- Radon 222