Mercury
Atomic number 80 means that every Mercury nucleus contains 80 protons. That proton count is the element's identity: change it and you no longer have Mercury.
Start with the nucleus
Atomic number 80 means that every Mercury nucleus contains 80 protons. That proton count is the element's identity: change it and you no longer have Mercury.
Mercury (Hg) is chemical element 80. It belongs to the transition metals, and its reference state at room temperature is a liquid. Those basic facts are a useful starting point for its chemistry and applications.
In practice, it turns up most often in measurement, lamps and chemical synthesis.
See the atom
Conceptual visual: electron shells are a learning aid, not a literal picture of quantum orbitals.
What this number means
Atomic number 80 means that every Mercury nucleus contains 80 protons. That proton count is the element's identity: change it and you no longer have Mercury.