Chemical Elements.com - Lanthanum (La)

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Basic Information

Name: Lanthanum
Symbol: La
Atomic Number: 57
Atomic Mass: 138.9055 amu
Melting Point: 920.0 °C (1193.15 K, 1688.0 °F)
Boiling Point: 3469.0 °C (3742.15 K, 6276.2 °F)
Number of Protons/Electrons: 57
Number of Neutrons: 82
Classification: Rare Earth
Crystal Structure: Hexagonal
Density @ 293 K: 6.7 g/cm³
Color: white

Atomic Structure

Number of Energy Levels: 6

First Energy Level:

Second Energy Level:

Third Energy Level:

Fourth Energy Level:

Fifth Energy Level:

Sixth Energy Level:

Isotopes

Isotope	Half Life
La-134	6.5 minutes
La-137	6000.0 years
La-138	1.05E10 years
La-139	Stable
La-140	1.67 days
La-141	3.9 hours
La-142	1.54 minutes

Facts

Date of Discovery: 1839
Discoverer: Carl Mosander
Name Origin: From the Greek word lanthaneis (to lie hidden)
Uses: expensive camera lenses
Obtained From: monazite, bastnasite

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