Question

Radon-222 is an alpha emitter with a half life of 3.82 days.

1. What is the mass number of the daughter isotope?
2. What is the element symbol of the daughter isotope?
3. What is the atomic number of the daughter isotope?​

Answer 1

The daughter isotope (a decay product): Polonium (Po)

Further explanation

Radioactivity is the process of unstable isotopes to stable isotopes by decay, by emitting certain particles,  

• alpha α particles ₂He⁴

• beta β ₋₁e⁰ particles
• gamma particles γ
• positron particles ₁e⁰

Radon-222 emits alpha α particles ₂He⁴  , so the atomic number decreases by 2, mass number decreases by 4

Reaction

$\tt _{86}^{222}Rn\Rightarrow _{84}^{218}+_2^4He$

1. The mass number of the daughter isotope = 218

2 and 3. If we look at the periodic system, the element with atomic number 84 is Polonium (Po)