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Protactinium (Pa) – Element 91 of the periodic table

Protactinium (symbol Pa) is element number 91 of the periodic table and belongs to the “Actinide” category. Its atomic mass is about 231.04, and its phase under standard conditions is Solid. This element sits in period 7 and the f-block (Actinides) of the periodic table, and its electrons are arranged in shells of 2, 8, 18, 32, 20, 9, 2. The short electron configuration of Protactinium is [Rn] 5f² 6d¹ 7s². Known uses of Protactinium include Scientific research and Sediment dating.

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Properties of Protactinium

Atomic number
91
Chemical symbol
Pa
Atomic mass
231.04
Category
Actinide
Period
7
Block
f
Phase
Solid
Protons
91
Electrons
91
Neutrons (approx.)
140
Electron shells
2, 8, 18, 32, 20, 9, 2
Outer-shell electrons
2
Discovered
William Crookes (1900)

Electron configuration of Protactinium

The electron configuration of Protactinium (Pa), with 91 electrons, is shown below. The last shell (shell 7) is highlighted:

Full configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f² 6s² 6p⁶ 6d¹ 7s²
Short configuration
[Rn] 5f² 6d¹ 7s²
Last shell
7s²

What is electron configuration and how is it written?

Electron shells of Protactinium

Distribution of 91 electrons of Protactinium across shells K to Q:

  1. K2
  2. L8
  3. M18
  4. N32
  5. O20
  6. P9
  7. Q2

What is a actinide?

The actinides are the 15 elements from actinium to lawrencium, part of the f-block, and all of them are radioactive.

Uses of Protactinium

Frequently asked questions about Protactinium

What is the atomic number of Protactinium?

The atomic number of Protactinium (Pa) is 91; that is, every atom of it has 91 protons.

What is the electron configuration of Protactinium?

The electron configuration of Protactinium (Pa) is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f² 6s² 6p⁶ 6d¹ 7s²; in short form it is [Rn] 5f² 6d¹ 7s², and its last shell is 7s².

What is the chemical symbol of Protactinium?

The chemical symbol of Protactinium is Pa.

Where is Protactinium located in the periodic table?

Protactinium is located in period 7 and the f-block (Actinides) and belongs to the “Actinide” category.

What is the atomic mass of Protactinium?

The atomic mass of Protactinium is about 231.04 (atomic mass units).

What is the phase of Protactinium under normal conditions?

The phase of Protactinium under standard conditions is Solid.

What are the uses of Protactinium?

Uses of Protactinium include Scientific research and Sediment dating.

Who discovered Protactinium?

Protactinium was discovered by William Crookes in 1900.

Elements in the same category as Protactinium (Actinide)

Actinium (Ac)Thorium (Th)Uranium (U)Neptunium (Np)Plutonium (Pu)Americium (Am)Curium (Cm)Berkelium (Bk)Californium (Cf)Einsteinium (Es)Fermium (Fm)Mendelevium (Md)Nobelium (No)Lawrencium (Lr)

See all Actinides