Identify the starting radioisotopes needed to balance each of these nuclear reactions:
a. ? + ⁴₂He → ¹¹³₄₉In
b. ? + ⁴₂He → ¹³₇N + ¹₀n

Verified step by step guidance

1. Step 1: Understand the nuclear reaction. The goal is to identify the missing radioisotope (denoted by '?') that balances the reaction. The reaction involves the addition of an alpha particle (⁴₂He) to an unknown isotope, producing plutonium-244 (²⁴⁴₉₄Pu) and a neutron (¹₀n).
2. Step 2: Apply the principle of conservation of mass number. The sum of the mass numbers (top numbers) on the left side of the equation must equal the sum of the mass numbers on the right side. For the right side, the mass numbers are 244 (Pu) + 1 (n) = 245. On the left side, the mass number of the unknown isotope plus 4 (He) must also equal 245.
3. Step 3: Apply the principle of conservation of atomic number. The sum of the atomic numbers (bottom numbers) on the left side must equal the sum of the atomic numbers on the right side. For the right side, the atomic numbers are 94 (Pu) + 0 (n) = 94. On the left side, the atomic number of the unknown isotope plus 2 (He) must also equal 94.
4. Step 4: Solve for the mass number and atomic number of the unknown isotope. Subtract the mass number and atomic number of the alpha particle (⁴₂He) from the totals on the right side to find the values for the unknown isotope.
5. Step 5: Identify the element corresponding to the calculated atomic number using the periodic table. The atomic number determines the element symbol, and the mass number completes the isotope notation.

Key Concepts

Nuclear Reactions

Nuclear reactions involve the transformation of atomic nuclei through processes such as fusion or fission. In these reactions, the total number of protons and neutrons must be conserved, meaning the sum of the atomic numbers and mass numbers on both sides of the equation must be equal. Understanding how to balance these equations is crucial for identifying the missing reactants or products.

Radioisotopes

Radioisotopes are unstable isotopes of elements that decay over time, emitting radiation in the process. They are often used in nuclear reactions as either reactants or products. Recognizing the specific radioisotopes involved in a reaction helps in determining the starting materials needed to achieve a balanced equation.

Conservation of Mass and Charge

In nuclear chemistry, the conservation of mass and charge states that the total mass and charge before a reaction must equal the total mass and charge after the reaction. This principle is essential for balancing nuclear equations, as it allows one to deduce the unknown reactants or products by ensuring that both mass numbers and atomic numbers are accounted for in the equation.