Mendeleev
Periodic table · chemistry · physics
Element story

Iridium

Atomic number 77 means that every Iridium nucleus contains 77 protons. That proton count is the element's identity: change it and you no longer have Iridium.

Start with the nucleus

Atomic number 77 means that every Iridium nucleus contains 77 protons. That proton count is the element's identity: change it and you no longer have Iridium.

Iridium (Ir) is chemical element 77. 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 spark plugs, crucibles and electronics.

See the atom

Conceptual visual: electron shells are a learning aid, not a literal picture of quantum orbitals.

What this number means

Atomic number 77 means that every Iridium nucleus contains 77 protons. That proton count is the element's identity: change it and you no longer have Iridium.

Keep exploring

→ Iridium · Atomic structure · Periodic trends

77IrIridium
Iridium · Ir · Z = 77

Iridium (Ir) is chemical element 77. 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.

Understanding the element

Iridium (Ir) is chemical element 77. 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.

Where do we encounter it?

In practice, it turns up most often in spark plugs, crucibles and electronics.

What its position in the table tells us

Iridium sits in period 6, group 9 and the D block. That location is useful because neighbouring elements often share trends in valence electrons, oxidation states and bonding behaviour.