Final answer:
Radon-220, represented as ¸86Rn¹20, decays by emitting an alpha particle (¸2He¹4), resulting in the daughter isotope polonium-218 (¸84Po¹218). This is expressed in the nuclear equation: ¸86Rn¹220 → ¸2He¹4 + ¸84Po¹218.
Step-by-step explanation:
The student has asked to express radon-220 as an isotope and to write the nuclear equation representing its radioactive decay by alpha particle emission.
Radon is a noble gas with the atomic number 86. The isotope radon-220 can be represented as ²86Rn¹220¸. During radioactive decay, an alpha particle, which is essentially a helium nucleus, is emitted. This alpha particle is represented as ¸2He¹4¸. Using the conservation of mass and atomic number in nuclear reactions, we subtract the mass and atomic numbers of the alpha particle from those of the parent radon-220 isotope. This subtraction (¹222 - 4 = 218 and 86 - 2 = 84) helps us identify the daughter isotope as polonium-218 (¸84Po¹218).
The nuclear equation for the decay of radon-220 is therefore:
¸86Rn¹220 → ¸2He¹4 + ¸84Po¹218