Lanthanum (La) – Periodic Table (Element Information & More)

This is a SUPER easy guide on Lanthanum element.

In fact, the table mentioned below is the perfect information box (Which gives you every single detail about the Lanthanum element in Periodic table.)

So if you want to know anything about Lanthanum element, then this guide is for you.

Let’s dive right into it!

Lanthanum Element (La) Information

Appearance	Silvery white metallic
State (at STP)	Solid
Position in Periodic table	Group: lanthanides, Period: 6, Block: d
Category	Lanthanides
Atomic number or  Protons	57
Neutrons	82
Electrons	57
Symbol	La
Atomic mass	138.91 u
Electrons arrangement or  Bohr model	2, 8, 18, 18, 9, 2
Electronic configuration	[Xe] 5d1 6s2
Atomic radius	240 picometers (van der Waals radius)
1st Ionization energy	5.577 eV
Electronegativity	1.1 (Pauling scale)
Crystal structure	Double hexagonal close packed
Melting point	1193 K or 920 °C or 1688 °F
Boiling point	3737 K or 3464 °C or 6267 °F
Density	6.15 g/cm3
Main isotope	139La
Who discovered Lanthanum and when?	Carl Gustaf Mosander in 1838
CAS number	7439-91-0

Lanthanum in Periodic table

Lanthanum element is in period 6 of the Periodic table. Lanthanum is the d-block element and it belongs to lanthanides group.

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Why is Lanthanum in Period 6?

Let me ask you a question.

How many shells does lanthanum have?

It’s 6. Right?

You have already seen the bohr model of lanthanum atom in the above table.

From the Bohr model, it can be found that the number of orbits or shells in lanthanum is 6. Hence, as lanthanum has 6 orbits, it lies in period 6 of the Periodic table. 

Why is Lanthanum in d-block?

Before knowing this reason, first of all I want to ask you a simple question.

How can you determine the blocks-wise position of elements?

The simple answer: The elements will lie in the s, p, d or f block will completely depend upon the subshell in which the last electron will enter.

For example; the electron configuration of lanthanum is [Xe] 6s² 5d¹.

So the last electron of lanthanum enters the d-subshell or d-orbital. 

Hence, lanthanum is the d-block element.

5 Interesting facts about Lanthanum

Interesting facts about lanthanum element are mentioned below.

1. The name Lanthanum was derived from the Greek word “lanthano”, which means “to be hidden”.
2. Lanthanum was discovered by Carl Gustaf Mosander in 1838.
3. Out of all the rare earth metals on the periodic table, lanthanum is the most reactive.
4. The concentration of lanthanum in the earth’s crust is approximately 32 ppm.
5. Lanthanum metal is not actually rare in quantity, but the fact is that it is spread evenly on the earth and it is very difficult to find this element at one place on the earth. Thus lanthanum is rare in the context of available resources.
6. China, Russia and Malaysia are the leading producers of lanthanum in the world.
7. Around 12500 tons of lanthanum is produced annually in the entire world.

Properties of Lanthanum

The physical and chemical properties of lanthanum element are mentioned below.

Physical properties of Lanthanum

Physical properties of lanthanum are mentioned below.

• Lanthanum is a solid metal having Silvery-white metallic appearance.
• Lanthanum is a soft metal that can be sliced with a kitchen knife.
• Lanthanum is a ductile as well as malleable metal.
• The melting point of lanthanum is 920 °C and its boiling point is 3464 °C.
• Lanthanum has the atomic mass 138.91 u and it has the density 6.15 g/cm³.
• The crystal structure of lanthanum is Double hexagonal close packed.
• There are many isotopes of lanthanum, but out of them the most abundant isotope is ¹³⁹La (which has an abundance of around 99.9%).

Chemical properties of Lanthanum

Chemical properties of lanthanum are mentioned below.

• Lanthanum is a reactive metal and it reacts with water at room temperature also.
• When freshly cut lanthanum metal is kept open in air, it reacts with the oxygen of the air and tarnishes easily.
• Lanthanum is also chemically reactive to boron, carbon, nitrogen as well as halogens of the periodic table.
• The first ionization energy of lanthanum is 5.577 eV.
• The electronegativity of lanthanum is 1.1 on the Pauling scale.

Uses of Lanthanum

Uses of lanthanum are mentioned below.

• Lanthanum oxide (which is a compound of lanthanum, has a high refractive index) is used in manufacturing of camera lenses as well as in other special glasses (including night vision glasses).
• In manufacturing industries, lanthanum is used in manufacturing nodular cast iron.
• Besides these, lanthanum also finds its application in carbon arc lighting which is used in studio lightings.
• Lanthanum is used in rechargeable batteries used in hybrid automobiles.

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External resources:

1. Lanthanum – Wikipedia. (2016, July 10). Lanthanum – Wikipedia. https://en.wikipedia.org/wiki/Lanthanum
2. Lanthanum – Element information, properties and uses | Periodic Table. (n.d.). Lanthanum – Element Information, Properties and Uses | Periodic Table. https://www.rsc.org/periodic-table/element/57/lanthanum
3. P. (n.d.). Lanthanum | La (Element) – PubChem. Lanthanum | La (Element) – PubChem. https://pubchem.ncbi.nlm.nih.gov/element/Lanthanum
4. It’s Elemental – The Element Lanthanum. (n.d.). It’s Elemental – the Element Lanthanum. https://education.jlab.org/itselemental/ele057.html
5. Periodic Table of Elements: Los Alamos National Laboratory. (n.d.). Periodic Table of Elements: Los Alamos National Laboratory. https://periodic.lanl.gov/57.shtml
6. Lanthanum | Encyclopedia.com. (2018, May 17). Lanthanum | Encyclopedia.com. https://www.encyclopedia.com/science-and-technology/chemistry/compounds-and-elements/lanthanum