Answer
(a) $_{88}^{220}Ra$
(b) $_{84}^{210}Po$
(c) $_{79}^{197}Au$
Work Step by Step
1. Use a periodic table to find the symbol and the atomic number for each indicated element:
(a) Radon: "Ra"; Z = 88
(b) Polonium: "Po"; Z = 84
(c) Gold: "Au"; Z = 79
2. Write the atomic number (Z), on the bottom left, and the mass of the element (A) on the top left of the symbol.
** The mass number is the one that follows the name of the compound:
(a) $_{88}^{220}Ra$
(b) $_{84}^{210}Po$
(c) $_{79}^{197}Au$
