Roentgenium
Atomic number 111 means that every Roentgenium nucleus contains 111 protons. That proton count is the element's identity: change it and you no longer have Roentgenium.
Start with the nucleus
Atomic number 111 means that every Roentgenium nucleus contains 111 protons. That proton count is the element's identity: change it and you no longer have Roentgenium.
Roentgenium (Rg) is chemical element 111. It belongs to the elements whose chemistry is still being explored, and its reference state at room temperature is not firmly established. Those basic facts are a useful starting point for its chemistry and applications.
In practice, it turns up most often in scientific research.
See the atom
Conceptual visual: electron shells are a learning aid, not a literal picture of quantum orbitals.
What this number means
Atomic number 111 means that every Roentgenium nucleus contains 111 protons. That proton count is the element's identity: change it and you no longer have Roentgenium.