Final answer:
The student's question pertains to balancing nuclear equations in chemistry, specifically high school chemistry. An example provided was balancing the decay of radon-226, which results in radium-222 and a helium nucleus. This reflects the conservation of mass and atomic number in nuclear reactions.
Step-by-step explanation:
The question involves balancing nuclear equations, which falls under the subject of chemistry, and is typically taught at the high school level. Balancing a nuclear equation is similar to balancing chemical equations, where the total mass numbers and atomic numbers must be the same on both sides of the reaction.
For the example provided, 226Rn → 222? + He, you need to balance the equation by identifying the missing element, which in this case would be 222Ra (Radium), because when Radium-222 undergoes alpha decay, it will emit a Helium nucleus, also known as an alpha particle, and the mass number will decrease by 4. This is due to the conservation of mass and atomic number during nuclear reactions.
Balancing equations involving oxidation-reduction is done by ensuring the number of electrons gained in the reduction half-reaction is equal to the number of electrons lost in the oxidation half-reaction. This can involve multiple steps, including separating the two half-reactions, balancing each for mass and charge, and then combining them together again.