Chemical Elements.com - Protactinium (Pa)

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Basic Information

Name: Protactinium
Symbol: Pa
Atomic Number: 91
Atomic Mass: 231.03587 amu
Melting Point: 1600.0 °C (1873.15 K, 2912.0 °F)
Boiling Point: Unknown
Number of Protons/Electrons: 91
Number of Neutrons: 140
Classification: Rare Earth
Crystal Structure: Orthorhombic
Density @ 293 K: 15.4 g/cm³
Color: Unknown

Atomic Structure

Number of Energy Levels: 7

First Energy Level:

Second Energy Level:

Third Energy Level:

Fourth Energy Level:

Fifth Energy Level:

Sixth Energy Level:

Seventh Energy Level:

Isotopes

Isotope	Half Life
Pa-230	17.4 days
Pa-231	32800.0 years
Pa-233	27.0 days
Pa-234	6.69 hours
Pa-234m	1.17 minutes

Facts

Date of Discovery: 1917
Discoverer: Fredrich Soddy
Name Origin: From the Greek word protos (first)
Uses: No uses known
Obtained From: fission product of uranium, thorium, plutonium

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