Question 210S: Short Answer
1.
Radium-226 has a half-life of 1600 years. How is it possible that it is found in rocks that are 10 9 years old?
2.
The isotope 235U decays into another element, emitting an alpha particle. What is the element?
This element decays, and the next, and so on until a stable element is reached. The complete list of particles emitted in
this chain is:
235
92
U  [ ,  ,  ,  ,  ,  ,  ,  ,  ,  ,  ]  X.
What is the stable element X? (You could write down each element in the series, but there is a quicker way.)
3.
The following fission reaction can take place in a nuclear reactor:
235
92
U  01n137
55 Cs 
94
[]
Rb  01n.
Complete the equation, showing how many neutrons are produced in the reaction. What is the significance of the
number of neutrons produced?
Why are the products of the reaction, caesium-137 and rubidium-94, likely to be radioactive? What type of decay are
these isotopes likely to show?
4.
Boron absorbs neutrons with results as follows:
10
5
B 01 n  73 Li 24 .
Why is boron suitable for use in a control rod?
5.
When the isotope
27
13
Al is irradiated with alpha particles, the products from each aluminium nucleus are a neutron,
and a nuclide which emits positrons to give the stable isotope
6.
30
14
Si . Write nuclear equations for these two processes.
Complete the following nuclear equations. In each case describe the decay process:
131
Xe  01e
53 I 
67
31
11
6
Ga  01 e  Zn
C  B  01e
Tc  Tc   .
The Manhattan Project, the development of the atomic bomb, led to the discovery of the transuranic elements
(elements beyond uranium in the periodic table). Plutonium, element 94, is formed by the bombardment of uranium238 with neutrons. The nuclear equations are:
99m
43
7.
238
92
U 01 n 239
92 U
239
92
0
U239
93 Np  1 e
239
93
0
Np 239
94 Pu 1 e
Complete the following nuclear equation for the formation of americium:
239
94
Pu  201 n  Am 
0
1
e.
Curium is produced if plutonium-239 is bombarded with alpha particles. If the curium isotope is , complete the
equation
239
94
Pu  24 
If curium is made the target for alpha particle bombardment californium is produced. Complete the nuclear equation
to find the atomic number of californium:
242
96
Cm  24  245 Cf  01 n.
By firing heavier particles such as carbon or boron ions at the target materials heavier elements can be synthesised.
Complete the nuclear equation (Lw is lawrencium)
252
Cf  95 B  Lw  401 n.
One of the transuranic elements is commonly found in the home. Which is this and where is it used?
8.
In January 1999, scientists at Dubna in Russia reported the first nucleus of element 114. It contained 175 neutrons.
They bombarded plutonium with a high-energy beam of calcium ions. The calcium was an extremely rare and
expensive isotope with 20 protons and 28 neutrons. The plutonium had 94 protons and 150 neutrons. Three neutrons
were lost as the two nuclei combined. The new element had a lifetime of 30 seconds. This new element lies on the
‘island of stability’. This island lies beyond the known world of nuclei charted on the N–Z plot. Write the nuclear
equation for the reaction. See where the island of stability lies on the N–Z plot.