Information valid for Pa-231 unless otherwise noted

Protactinium

Basic Information

Symbol: Pa
Atomic Number: 91
Mass: 231.03587
Melting Point: 1600.0 C
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: 2 Second Energy Level: 8 Third Energy Level: 18 Fourth Energy Level: 32 Fifth Energy Level: 20 Sixth Energy Level: 9 Seventh Energy Level: 2

Isotopes

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