Rhodium
Atomic number 45 means that every Rhodium nucleus contains 45 protons. That proton count is the element's identity: change it and you no longer have Rhodium.
Start with the nucleus
Atomic number 45 means that every Rhodium nucleus contains 45 protons. That proton count is the element's identity: change it and you no longer have Rhodium.
Rhodium (Rh) is chemical element 45. It belongs to the transition metals, and its reference state at room temperature is a solid. Those basic facts are a useful starting point for its chemistry and applications.
In practice, it turns up most often in catalysts, reflectors and jewellery.
See the atom
Conceptual visual: electron shells are a learning aid, not a literal picture of quantum orbitals.
What this number means
Atomic number 45 means that every Rhodium nucleus contains 45 protons. That proton count is the element's identity: change it and you no longer have Rhodium.