Question

Activity 1.1 Write the nuclear reactions involved in the
synthesis of each of the following new elements:
a. Curium (Z 96) was formed by reacting Pu - 239 with alpha
particles 42He. It has a half-life of 162 days.
b. Mendelevium (Z = 101) was formed by reacting En-253 with alpha
particles.
C. Meitnerium (Z = 109) was formed by cold fusion which involves the
combination of Bi and Fe nuclides at ordinary temperature​

Answer 1

Answer:

When a nucleus captures a neutron, it often tries to correct for its neutron excess by beta decay, turning a neutron into a proton and thus creating an atom with atomic number Z increased by one unit. This commonly observed phenomenon suggests a way to create new elements of increased atomic number and thus to create ever more massive elements that are not found on Earth. Most of these elements are radioactive, with very short half-lives. However, theories of nuclear structure predict that at a certain atomic number, which is currently beyond present experimental limits, new long-lived nuclei can be created.

The most massive naturally occurring element on Earth is uranium (U), with a nucleus of 92 protons. In 1934, scientists started the search for more massive elements with 93 or more protons. They succeeded in 1940 when neptunium (Np, Z = 93) was synthesized at the University of California, Berkeley. Edwin McMillan and Philip Abelson observed Np while studying fission products produced in the bombardment of 238U with thermal neutrons. They found a radioactive reaction product that was not a fission product. This product was formed by the capture of a neutron to produce 239U, which subsequently b- decayed to 239Np via the reaction

239U + 1n Æ 239U (23.5 min) Æ 239Np (2.36 d),

Answer 2

a)  Curium (Mass number = 96) is formed by reacting Pu(Mass number = 239) with alpha  particles He (Mass number = 4).

${239} \atop {94}} \right.$Pu + ${4} \atop 2}} \right.$He -> ${{242} \atop {96}} \right.$Cm + ${1} \atop {0}} \right.$n

b) Mendelevium (Mass number = 101) is formed by reacting En (Mass number = 253) with alpha  particles He(Mass number = 4)

${253} \atop {99}} \right.$Es + ${4} \atop 2}} \right.$He -> ${{256} \atop {101}} \right.$Md + ${1} \atop {0}} \right.$n

c) Meitnerium (Mass number = 109) is formed by cold fusion which involves the  combination of Bi and Fe nuclides at ordinary temperature.​

${209} \atop {83}} \right.$Bi + ${26} \atop 56}} \right.$Fe -> ${{266} \atop {109}} \right.$Mt + ${1} \atop {0}} \right.$n