Introduction
Np is most often extracted from spent nuclear fuel rods as a by-product of plutonium production.
Artificial 237Np is produced through the reduction of 237NpF3 with barium or lithium vapour at 12000C.
2NpF3 + 3Ba → 2Np + 3BaF2
When uranium atom is bombarded with slow moving neutron, 239Np was produced. It was first transuranium element. At the time 23 minute. Elimination of β- particle occurs, Neptunium is obtained.
92U238 + 0n1 → 92U239 → 93Np239
Synthesis of Atomic number 93
When a 235U atom captures a neutron, it is converted to an excited state of 236U. About 81% of the excited 236U nuclei undergo fission, but the remainder decay to the ground state of 236U by emitting gamma radiation. Further neutron capture creates 237U which has a half-life of 7 days and thus quickly decays to 237Np through beta decay. During beta decay, the excited 237U emits an electron, while the atomic weak interaction converts a neutron to a proton, thus creating 237Np.
92U235 + 0n1 → 92Um236 → 92U236 + γ
92U236 + 0n1 → 92U237 → 93Np237
- From periodic table Atomic number 93 is ‘Neptunium’.
- Chemical symbol is ‘Np’.
- Neptunium as atomic number is 93 and mass number is 237.0482
- Neptunium belongs to f-block element because the atom has valence electron in f-orbital.
- f-block elements are also called inner transition elements.
- In Neptunium the outermost electrons are in 5f-orbitals
- Neptunium atom belongs to actinide series.
- It has electronic configuration [Rn], 7s2, 6d1, 5f2
- It occurs in solid state in nature.
- Atomic number 93 was discovered by Edwin Mcmillan and Philip H. Abelson in the year 1940 in Berkeley, California.
- Trace amount of Neptunium are naturally found as a decay product from transmutation reaction in uranium ores.
Np is most often extracted from spent nuclear fuel rods as a by-product of plutonium production.
Artificial 237Np is produced through the reduction of 237NpF3 with barium or lithium vapour at 12000C.
2NpF3 + 3Ba → 2Np + 3BaF2
When uranium atom is bombarded with slow moving neutron, 239Np was produced. It was first transuranium element. At the time 23 minute. Elimination of β- particle occurs, Neptunium is obtained.
92U238 + 0n1 → 92U239 → 93Np239
Properties of Atomic number 93
- Neptunium element has density 20.45g/cm3.
- It has melting point 910K and high boiling point of 4273K.
- It has oxidation state 7, 6, 5, 4, 3.
- Atomic number 93 has atomic radius 155pm.
- Neptunium has three crystal structure forms.
Half life of Np
There are nineteen neptunium radioisotopes which have been characterized, with the most stable being 237Np with a half-life of 2.14 million years, 236Np with a half-life of 154,000 years, and 235Np with a half-life of 396.1 days. All of the remaining radioactiveMeta states, with the most stable being 236Np which as half life of 22.5 hours. isotopes have half-lives which have less than 4.5 days, and the majority of these have half-lives that are less than 50 minutes. This element also has 4Synthesis of Atomic number 93
When a 235U atom captures a neutron, it is converted to an excited state of 236U. About 81% of the excited 236U nuclei undergo fission, but the remainder decay to the ground state of 236U by emitting gamma radiation. Further neutron capture creates 237U which has a half-life of 7 days and thus quickly decays to 237Np through beta decay. During beta decay, the excited 237U emits an electron, while the atomic weak interaction converts a neutron to a proton, thus creating 237Np.
92U235 + 0n1 → 92Um236 → 92U236 + γ
92U236 + 0n1 → 92U237 → 93Np237
Uses of Atomic number 93
- 237Np is irradiated with neutrons to create 238Pu, an alpha emitter for radioisotope thermal generators for spacecraft and military applications. 237Np will capture a neutron to form 238Np and beta decay with a half life of two days to produce 238Pu.
- Np is fissionable, and could be theoretically be used as fuel in a fast neutron reactor or nuclear weapon.
- 237Np is used in devices for detecting high-energy (MeV) neutrons.
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