Meitnerium
Atomic number 109 means that every Meitnerium nucleus contains 109 protons. That proton count is the element's identity: change it and you no longer have Meitnerium.
Start with the nucleus
Atomic number 109 means that every Meitnerium nucleus contains 109 protons. That proton count is the element's identity: change it and you no longer have Meitnerium.
Meitnerium (Mt) is chemical element 109. 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 109 means that every Meitnerium nucleus contains 109 protons. That proton count is the element's identity: change it and you no longer have Meitnerium.