Indium
Atomic number 49 means that every Indium nucleus contains 49 protons. That proton count is the element's identity: change it and you no longer have Indium.
Start with the nucleus
Atomic number 49 means that every Indium nucleus contains 49 protons. That proton count is the element's identity: change it and you no longer have Indium.
Indium (In) is chemical element 49. It belongs to the post-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 touch screens, semiconductors and alloys.
See the atom
Conceptual visual: electron shells are a learning aid, not a literal picture of quantum orbitals.
What this number means
Atomic number 49 means that every Indium nucleus contains 49 protons. That proton count is the element's identity: change it and you no longer have Indium.