Problem 34 - Chemistry: The Central Science

Question

In 1930 the American physicist Ernest Lawrence designed the first cyclotron in Berkeley, California. In 1937 Lawrence bombarded a molybdenum target with deuterium ions, producing for the first time an element not found in nature. What was this element? Starting with molybdenum- 96 as your reactant, write a nuclear equation to represent this process.

Step-by-Step Solution

Answer

The element produced by bombarding molybdenum-96 with deuterium ions is Technetium-98. The nuclear equation for this process is: \({}^{96}_{42}\textrm{Mo} + {}^{2}_{1}\textrm{H} \rightarrow {}^{98}_{43}\textrm{Tc} + n\)

Step 1: Identify the target element and bombarding particle

The target element is molybdenum-96 (Mo-96), which has an atomic number of 42 and a mass number of 96. The bombarding particle is a deuterium ion, which is an isotope of hydrogen with one proton, one neutron, and an atomic number of 1.

Step 2: Determine the mass and atomic numbers of the resulting element

Since both the target element and the bombarding particle's nucleus are involved in the reaction, we need to consider the addition of their mass numbers and atomic numbers to find the resulting element. The mass number of the deuterium ion is 2 (1 proton + 1 neutron). The mass number of the resulting element: \(96+2=98\) The atomic number of the resulting element: \(42+1=43\)

Step 3: Identify the resulting element

The element produced by the reaction has an atomic number of 43 and a mass number of 98. Checking a periodic table, we find that the element with an atomic number of 43 is Technetium (Tc). Therefore, the resulting element is Technetium-98 (Tc-98).

Step 4: Write the nuclear equation

To write the balanced nuclear equation, we need to represent the target element, bombarding particle, and the resulting element with their respective symbols and mass and atomic numbers. We should also include any other particles or energy that might be released during the reaction. Molybdenum-96 (Mo-96): \({}^{96}_{42}\textrm{Mo}\) Deuterium ion: \({}^{2}_{1}\textrm{H}\) Technetium-98 (Tc-98): \({}^{98}_{43}\textrm{Tc}\) The nuclear equation for the reaction is: \({}^{96}_{42}\textrm{Mo} + {}^{2}_{1}\textrm{H} \rightarrow {}^{98}_{43}\textrm{Tc} + n\) In this equation, "n" represents a neutron. This neutron is included to ensure the conservation of charge and mass during this nuclear reaction, as an additional neutron is needed to balance the equation.

Key Concepts

Cyclotron

A cyclotron is a type of particle accelerator, invented in the 1930s by Ernest Lawrence, which is designed to accelerate charged particles along a spiral pathway within a magnetic field. It works on the principle that charged particles moving perpendicular to a magnetic field experience a force that causes them to move in a circular path. The particles receive continuous boosts in energy from a high-frequency alternating electric field, which makes them move in outward spirals until they attain the desired energy level.

Using a cyclotron, scientists can create high-energy particles that are then used to initiate nuclear reactions. These reactions often result in the formation of new elements or isotopes not commonly found in nature. The breakthrough Lawrence achieved in 1937 demonstrated the ability of cyclotron to transform elements, which is not only pivotal in scientific research but also has practical applications in medicine, such as producing isotopes for medical imaging.

Nuclear Reaction

A nuclear reaction involves the collision of atomic nuclei or the interaction between a nucleus and a subatomic particle. During this process, the nuclei might merge, break apart, or undergo a nuclear decay, leading to a transformation in the number of protons, neutrons, or both within the nucleus. This change can result in the production of a different isotope or even a different element altogether, as was the case when Lawrence bombarded molybdenum to produce technetium.

Furthermore, nuclear reactions are accompanied by a tremendous release or absorption of energy, which can be utilized for power generation in nuclear reactors, or observed in the destructive power of nuclear weaponry. In Ernest Lawrence's experiment, the collision between a deuterium ion and molybdenum-96 resulted in the emission of a neutron and the creation of a new element, technetium-98, which emphasizes the transformative power of nuclear reactions.

Isotopes

Isotopes are variants of elements that have the same number of protons but differ in the number of neutrons within their nuclei. This difference in neutron number means that isotopes of the same element can have varied mass numbers, even though they share chemical properties. For example, deuterium is an isotope of hydrogen with one neutron, as opposed to the most common hydrogen isotope, protium, which has none.

The existence of isotopes is fundamental to nuclear chemistry and physics because it allows for the exploration of different nuclear reactions involving the same element. The manipulation of isotopes through nuclear reactions has various applications, including medical imaging, radiometric dating, and as tracers in biochemical research. The cyclotron's ability to accelerate isotopes like deuterium is essential in facilitating innovative research and technological developments across multiple scientific fields.