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Lanthanum (La) – Element 57 of the periodic table

Lanthanum (symbol La) is element number 57 of the periodic table and belongs to the “Lanthanide” category. Its atomic mass is about 138.91, and its phase under standard conditions is Solid. This element sits in period 6 and the f-block (Lanthanides) of the periodic table, and its electrons are arranged in shells of 2, 8, 18, 18, 9, 2. The short electron configuration of Lanthanum is [Xe] 5d¹ 6s². Known uses of Lanthanum include Camera lenses, Nickel-metal hydride batteries and Petrochemicals.

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Properties of Lanthanum

Atomic number
57
Chemical symbol
La
Atomic mass
138.91
Category
Lanthanide
Period
6
Block
f
Phase
Solid
Protons
57
Electrons
57
Neutrons (approx.)
82
Electron shells
2, 8, 18, 18, 9, 2
Outer-shell electrons
2
Discovered
Carl Gustaf Mosander (1839)

Electron configuration of Lanthanum

The electron configuration of Lanthanum (La), with 57 electrons, is shown below. The last shell (shell 6) is highlighted:

Full configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 5d¹ 6s²
Short configuration
[Xe] 5d¹ 6s²
Last shell
6s²

What is electron configuration and how is it written?

Electron shells of Lanthanum

Distribution of 57 electrons of Lanthanum across shells K to P:

  1. K2
  2. L8
  3. M18
  4. N18
  5. O9
  6. P2

What is a lanthanide?

The lanthanides are the 15 elements from lanthanum to lutetium, part of the f-block, with very similar chemical properties; they are often grouped among the “rare earths”.

Uses of Lanthanum

Frequently asked questions about Lanthanum

What is the atomic number of Lanthanum?

The atomic number of Lanthanum (La) is 57; that is, every atom of it has 57 protons.

What is the electron configuration of Lanthanum?

The electron configuration of Lanthanum (La) is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 5d¹ 6s²; in short form it is [Xe] 5d¹ 6s², and its last shell is 6s².

What is the chemical symbol of Lanthanum?

The chemical symbol of Lanthanum is La.

Where is Lanthanum located in the periodic table?

Lanthanum is located in period 6 and the f-block (Lanthanides) and belongs to the “Lanthanide” category.

What is the atomic mass of Lanthanum?

The atomic mass of Lanthanum is about 138.91 (atomic mass units).

What is the phase of Lanthanum under normal conditions?

The phase of Lanthanum under standard conditions is Solid.

What are the uses of Lanthanum?

Uses of Lanthanum include Camera lenses, Nickel-metal hydride batteries and Petrochemicals.

Who discovered Lanthanum?

Lanthanum was discovered by Carl Gustaf Mosander in 1839.

Elements in the same category as Lanthanum (Lanthanide)

Cerium (Ce)Praseodymium (Pr)Neodymium (Nd)Promethium (Pm)Samarium (Sm)Europium (Eu)Gadolinium (Gd)Terbium (Tb)Dysprosium (Dy)Holmium (Ho)Erbium (Er)Thulium (Tm)Ytterbium (Yb)Lutetium (Lu)

See all Lanthanides