The element that has 91 electrons is Protactinium.
Protactinium (Pa) is a rare, dense, and silvery-white actinide metal. In its neutral atomic state, an element's number of electrons is equal to its atomic number, which also represents the number of protons in its nucleus. Therefore, an element with 91 electrons is Protactinium, as its atomic number is 91.
Key Characteristics of Protactinium (Pa)
Protactinium is a fascinating and highly radioactive element, primarily known for its role in nuclear science and as an intermediate product in the decay chains of uranium. Here are some of its notable properties:
- Atomic Number: 91
- Symbol: Pa
- Classification: Actinide, a group of metallic radioactive elements with atomic numbers from 89 (Actinium) to 103 (Lawrencium).
- Natural Occurrence: Protactinium occurs naturally in very small concentrations in uranium ores.
| Property | Value |
|---|---|
| Number of Electrons | 91 |
| Melting Point | 1600.0° C |
| Boiling Point | Unknown |
| Density | 15.4 grams per cubic centimeter |
Discovery and Isotopes
Protactinium was initially discovered in 1913 by Kasimir Fajans and Oswald H. Göhring, who found the short-lived isotope protactinium-234. Later, in 1918, Otto Hahn and Lise Meitner, along with Frederick Soddy and John Cranston, independently discovered the longer-lived isotope, protactinium-231. This latter isotope is the most stable and abundant form found in nature, with a half-life of approximately 32,760 years.
Applications and Significance
Due to its high radioactivity, scarcity, and toxicity, Protactinium has limited practical applications. It is primarily used in scientific research, particularly in the study of nuclear physics and as a tracer in geochemical and oceanographic studies to understand sediment deposition rates and marine processes.
For more information about elements and their properties, you can explore the Periodic Table of Elements.
