Mendeleev
Periodic table · chemistry · physics
Element story

Lanthanum

Atomic number 57 means that every Lanthanum nucleus contains 57 protons. That proton count is the element's identity: change it and you no longer have Lanthanum.

Start with the nucleus

Atomic number 57 means that every Lanthanum nucleus contains 57 protons. That proton count is the element's identity: change it and you no longer have Lanthanum.

Lanthanum (La) is chemical element 57. It belongs to the lanthanoids, 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 optical lenses, batteries and catalysts.

See the atom

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

What this number means

Atomic number 57 means that every Lanthanum nucleus contains 57 protons. That proton count is the element's identity: change it and you no longer have Lanthanum.

Keep exploring

→ Lanthanum · Atomic structure · Periodic trends

57LaLanthanum
Lanthanum · La · Z = 57

Lanthanum (La) is chemical element 57. It belongs to the lanthanoids, 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

Lanthanum (La) is chemical element 57. It belongs to the lanthanoids, 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 optical lenses, batteries and catalysts.

What its position in the table tells us

Lanthanum sits in period 6, group 3 and the D block. That location is useful because neighbouring elements often share trends in valence electrons, oxidation states and bonding behaviour.