Question

In the Middle Ages, alchemists attempted to transmute base metals into gold. Recently, platinum has been transmuted into gold by bombarding Pt-198 with a deuterium nucleus to give a platinum nuclide and a proton. If the platinum nuclide decays by beta emission, what nuclide results?

Short answer

The resulting nuclide is a heavier isotope of platinum.

Step-by-step solution

Understand the Initial Reaction

The exercise involves bombarding Pt-198 with a deuterium nucleus. A deuterium nucleus consists of one proton and one neutron. When Pt-198 is hit by this deuterium, it absorbs the neutron and ejects a proton. This changes the atom into a different isotope of platinum.

Find the New Platinum Isotope

When the deuterium nucleus interacts with Pt-198, the neutron is added to the nucleus, while a proton is ejected. Since the mass number of Pt-198 was originally 198, adding one neutron changes it to 199, while the atomic number decreases by one due to the ejection of a proton, changing platinum (Z=78) into another element.

Determine Beta Decay Outcome

Beta emission turns a neutron into a proton, increasing the atomic number by one. Here, the platinum isotope (atomic number 77) which resulted from the earlier step after losing a proton (originally platinum atomic number 78 becomes 77) now undergoes beta decay. This increases the atomic number back to 78, transforming it back into a platinum isotope.

Identify the Resulting Nuclide

Since the beta decay reverses the change made by proton ejection (it adds a proton), the resulting nuclide is once again platinum, specifically a heavier isotope than the original Pt-198 due to the neutron added initially. Therefore, the final nuclide remains as a platinum isotope.

Key concepts

Beta Decay

Beta decay is an intriguing process where a neutron in the nucleus is transformed into a proton. During this transformation, an electron, known as a beta particle, and an antineutrino are ejected from the nucleus. This change effectively increases the atomic number by one, without altering the mass number.
Imagine a neutron inside the nucleus deciding to switch roles and become a proton. In doing so, it has to release some particles to balance the process — these are the beta particle and the antineutrino.
Beta decay is a type of radioactive decay and plays a crucial role in the stability of isotopes. It allows nuclei to achieve a more stable configuration by altering the balance of protons and neutrons. In the context of our exercise, after initial proton ejection reduced the atomic number of platinum, the isotope undergoes beta decay. This very effectively increases the atomic number by one, converting it back into a stable form of platinum that has the characteristics of increased mass number due to the additional neutron.

Isotopes

Isotopes are variants of a particular chemical element that have the same number of protons but different numbers of neutrons. This means that while they share the same atomic number, their mass numbers will differ.
To put it simply, isotopes are like sibling versions of an element. They have similar "personalities" because they have the same protons, but their "weight" or mass is different because of the different number of neutrons.

• The atomic number remains the same, as it equals the number of protons.
• The mass number changes, as it is the sum of protons plus neutrons.

In the exercise, we see Pt-198 experiencing a series of changes which eventually lead to a different isotope of platinum. Even though this isotope has a mass number of 199 rather than 198, it still retains its identity as a form of platinum because its atomic structure, specifically the number of protons, remains constant overall even though changes in neutron count temporarily altered it.

Nuclear Transmutation

Nuclear transmutation refers to the transformation of one chemical element or isotope into another. In the context of nuclear reactions, this occurs because of changes in the number of protons within the nucleus. Such changes can happen through various nuclear processes like nuclear fission, fusion, or observable in our scenario, particle bombardment.
Transmutation isn’t just historical alchemy; it's a reality in nuclear chemistry, usable and fascinating in modern applications. Via intentional bombardment of an element with particles, scientists can alter the nuclear structure resulting in new elements or isotopes. During the exercise, transmutation takes place when a platinum atom undergoes the bombardment with a deuterium nucleus.

• This incorporates a neutron into the nucleus.
• A proton is ejected, changing the atomic number.
• The transmuted element briefly becomes a different isotope before undergoing beta decay to revert to a form of platinum.

As seen here, transmutation serves as a step towards the resulting modified isotope of platinum. This showcases the complex dance of atomic interactions beyond simple chemical reactions, diving into the realm where atomic nuclei are manipulated.