Problem 42 - Chemistry and Chemical Reactivity

Question

To synthesize the heavier transuranium elements, a nucleus must be bombarded with a relatively large particle. If you know the products are californium- 246 and four neutrons, with what particle would you bombard uranium-238 atoms?

Step-by-Step Solution

Answer

The bombardment particle is carbon-12 (\(^{12}_{6}\text{C}\)).

Step 1: Understand the Given Products

The exercise states that the products of the reaction are californium-246 and four neutrons. This means that the nuclear reaction has a final format of \[ \text{Product} \rightarrow \text{Californium-246} + 4 \text{neutrons} \].

Step 2: Analyze the Reaction Requirements

To find the particle used in the bombardment, recall that the initial uranium, when bombarded, should lead to the products: californium-246 and 4 neutrons. The atomic number of Californium (Cf) is 98 and its mass number is 246. Neutrons have a mass number of 1 and are neutral in charge.

Step 3: Balance Mass Numbers

The mass number of the reactant uranium is \(238\). The product has a mass number of \(246\) (from Cf) and \(4 \times 1 = 4\) (from four neutrons), totaling 250. Thus, the bombarding particle must have contributed a net mass number change of \(250 - 238 = 12\).

Step 4: Balance Atomic Numbers

The atomic number of uranium is 92. The bombarding particle needs to account for the difference in atomic number between uranium and californium. The atomic number of californium is 98. Therefore, the particle should increase the atomic number by \(98 - 92 = 6\).

Step 5: Identify the Bombarding Particle

Considering that the particle adds a mass number of 12 and an atomic number of 6, this corresponds to a carbon nucleus (\(^{12}_{6}\text{C}\)). Carbon has a mass number of 12 and an atomic number of 6.

Key Concepts

Transuranium Elements

Transuranium elements are chemical elements with atomic numbers greater than 92, meaning they follow uranium on the periodic table. They are not typically found in nature as they are synthetic and tend to decay rapidly.

• These elements are produced artificially in laboratories through nuclear reactions by bombarding target nuclei with various particles.
• The process involves increasing the atomic number and sometimes the mass number of the target element.
• Commonly, these reactions occur in particle accelerators, where target nuclei like uranium or plutonium are bombarded.

The synthesis of transuranium elements is important for understanding nuclear chemistry and studying the properties of these artificially created elements. They also have applications in various fields such as medicine and research. One famous example is californium, which plays a crucial role in neutron analysis and cancer treatment.

Californium Synthesis

Californium is one of the transuranium elements, and its synthesis is a notable achievement in nuclear chemistry. The creation of californium involves a nuclear reaction with a heavy target like uranium.

• Typically, particles such as carbon or boron nuclei are used for bombardment because they have the ideal properties for producing heavier elements.
• In californium synthesis, a carbon nucleus can be used to bombard uranium-238, resulting in californium-246 and the release of neutrons.

The reaction balances both the mass number and atomic number across reactants and products to create californium successfully. This creation highlights the delicate balance required in nuclear reactions to achieve the desired elements. The complexity of this synthesis showcases the precision needed in the field of nuclear science.

Neutron Bombardment

Neutron bombardment is a pivotal technique used in the formation of new elements and for inducing nuclear reactions. This process involves targeting atomic nuclei with a stream of neutrons.

• Neutrons are neutral, allowing them to penetrate atomic nuclei without being repelled by positive charge, which is a barrier for charged particles.
• The absence of electric charge means neutrons can easily reach and interact with the atomic nucleus, often resulting in the absorption and possible transformation of the nucleus.
• Neutron bombardment can produce isotopes that might not otherwise be accessible, providing researchers with valuable data about nuclear physics and element behaviors.

In nuclear chemistry, neutron bombardment is essential not just for creating heavy elements, but also for analyzing and manipulating existing elements. It represents a cornerstone of experimental nuclear physics, offering insights into both theoretical and practical applications.