Np or neptunium is the fourth member of the actinide series having radioactive nature. Let us discuss some facts related to neptunium in this article.
Neptunium is a heavy metal in the actinide series. Due to its radioactive nature, it has isotopes with a short life. Neptunium is the first transuranic element in the periodic table. It can be synthesized by the nuclear irradiation of neptunium.
In this article we will learn some characteristics of neptunium in the periodic table like its symbol, atomic mass, melting point, etc.
1. Neptunium symbol
The atomic symbol for neptunium is “Np” which is the predominant letter of the English alphabet of the element.
2. Neptunium group in the periodic table
Neptunium does not have any particular group like other actinides. Due to actinide contraction, it is placed in between the 3rd and 4th group in the periodic table. 5f orbital is mainly responsible for this contraction.
3. Neptunium period in the periodic table
Np is placed in the 7th period because last available principle quantum number for neptunium is 7. The period of the neptunium is judged by the number of electrons which is greater than 86.
4. Neptunium block in the periodic table
Neptunium belongs to the f-block of the periodic table, as it has 5f orbital as the valence orbital.
5. Neptunium atomic number
The atomic number of neptunium is 93 which means it has 93 electrons in the different orbitals.
6. Neptunium atomic Weight
The mass of one atom of neptunium is 237 according to the 12C scale, which indicates neptunium is 237/12th times carbon.
7. Neptunium Electronegativity according to Pauling
The electronegativity is recorded at 1.36 for neptunium as per the Pauling scale, which indicates that it is most electropositive in nature.
8. Neptunium atomic Density
The atomic density of neptunium is found to be 20.2 g/cm3 which indicates that it belongs to a super heavy element.
9. Neptunium melting point
The melting point of neptunium is low 6440C or 914K, as lower energy is required to break weak crystals like orthorhombic.
10. Neptunium boiling point
Neptunium has a higher boiling point of 39020C to 4175K as it is a super heavy element and needs more energy to get boiled off from liquid to a gaseous state.
11. Neptunium Van der Waals radius
The van der Waal’s radius of neptunium is 200 pm because
- Neptunium has a 6s orbital which is subject to relativistic contraction
- Neptunium has 6d and 5f orbital which has a poor shielding effect and for this reason nucleus attracted the outermost electron towards itself and shortens the radius
12. Neptunium ionic radius
The ionic radius of neptunium is 200 pm because, in the ionic form, it can make a mono cation.
13. Neptunium isotopes
Elements having the same number of electrons but different mass numbers are called isotopes of the original element. Let us discuss the isotopes of Neptunium.
Based on its radioactive nature and neutron numbers it has 29 isotopes –
- 219Np
- 220Np
- 221Np
- 222Np
- 223Np
- 224Np
- 225Np
- 226Np
- 227Np
- 228Np
- 229Np
- 230Np
- 231Np
- 232Np
- 233Np
- 234Np
- 235Np
- 236Np
- 236mNp
- 238Np
- 238mNp
- 239Np
- 240Np
- 240mNp
- 241Np
- 242Np
- 243Np
- 244Np
Only 4 isotopes of Neptunium are stable which are discussed below
| Isotope | Natural Abundance | Half-life | Emitting particles | No. of Neutron |
| 235Np | Synthetic | 396.1 d | α, € | 142 |
| 236Np | Synthetic | 1.5*105 y | α, €, β | 143 |
| 237Np | trace | 2.14*106 y | α | 144 |
| 238U | trace | 2.35 d | β | 145 |
14. Neptunium electronic shell
The shell surrounding the nucleus as per principal quantum number and holding the electrons is called an electronic shell. Let us discuss the electronic shell of neptunium.
2 8 18 32 22 9 2 represents the correct electronic shell of neptunium as it has 93 electrons and to arrange those electrons in the set of orbitals we get this type of electronic shell around the nucleus in 1 to 7th orbital.
15. Neptunium electron configurations
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f4 6s2 6p6 6d3 7s2 or [Rn]5f46d17s2 represent the electronic configuration of neptunium as per Hund’s rule. Here we arrange 93 electrons by the Aufbau principle in every orbital.
16. Neptunium energy of first ionization
Neptunium requires 604.5 KJ/mol to remove the first electron from 7s and this is the value of the first ionization energy for the element.
17. Neptunium energy of second ionization
The energy required for the process is 1128KJ/mol as the 2nd electron is also removed from 7s orbital as it contains two electrons and because it is removed from the exciting system.
18. Neptunium energy of third ionization
The third I.E. for neptunium is 1997KJ/mol because it has the following reasons:
- Neptunium has a 6s orbital and due to relativistic contraction, it has the strongest shielding effect so more energy will be required.
- Along with 6s orbital, it has 5f and 6d orbital which have poor shielding effect so the nucleus attraction will be high
- The third ionization occurs from the super exciting state of neptunium.
19. Neptunium oxidation states
Np has variable valency or oxidation state from +2 to +7, although it is an actinide. +5 oxidation state is more stable than any other oxidation state of Np.
20. Neptunium CAS number
The CAS number of the Neptunium molecule is 7439-99-8, which is given by the chemical abstracts service.
21. Neptunium Chem Spider ID
The Chem Spider ID for Neptunium is 94588. By using this number, we can evaluate all the chemical data related to the Neptunium atom.
22. Neptunium allotropic forms
Allotropes are elements or molecules with similar chemical properties but different physical properties. Let us discuss the allotropic form of neptunium.
Neptunium has three allotropic forms and they are –
- α-Neptunium – which is orthorhombic in structure and stable at room temperature.
- β-Neptunium – adopts a tetragonal lattice structure and exists at above 2800C.
- γ-Neptunium – it has a cubic structure and is stable at above 5770C.
23. Neptunium chemical classification
The chemical classification of neptunium are –
- Np is the rare earth element
- Np is actinide heavy metal
- Np is a weakly radioactive element
- Np is transuranic element
24. Neptunium state at room temperature
Being a solid at room temperature Np adopts orthorhombic crystal in its lattice form.
25. Is Neptunium paramagnetic?
Paramagnetism is the tendency of magnetization in the direction of the magnetic field. Let us see whether Neptunium is paramagnetic or not.
Neptunium shows paramagnetism as it has four unpaired electrons in valence 5f orbital and the value is not only dependent on the spin of electrons but there is some sort of orbital contribution as well.
Conclusion
Neptunium is a radioactive element so it can be used in nuclear reactors and making different or higher-order radioactive isotopes. It is a transuranic element so it has the same kind of properties as uranium and the +5 oxidation state is the most stable form of neptunium where it can form various organometallic clusters.
Hi……I am Biswarup Chandra Dey, I have completed my Master’s in Chemistry from the Central University of Punjab. My area of specialization is Inorganic Chemistry. Chemistry is not all about reading line by line and memorizing, it is a concept to understand in an easy way and here I am sharing with you the concept about chemistry which I learn because knowledge is worth to share it.
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