Answer
Missing atom: $^{209}_{83}Bi$
Complete reaction:
$^{209}_{83}Bi + ^{64}_{28}Ni -- \gt ^{272}_{111}Rg + ^1_0n $
Work Step by Step
1. Find the mass number of the missing element.
The total mass number of the left side must be equal to that of the right side.
$? + 64 = 272 + 1$
$? + 64 = 273$
$? = 273 - 64$
$?= 209$
2. Find the atomic number of the missing element.
The tota l atomic number of the left side must be equal to that of the right side.
$? + 28 = 111 + 0$
$? = 111 - 28$
$? = 83$
3. Identify the symbol of the element with atomic number equal to 83:
It is "Bi".
4. Now, write the complete symbol, and substitute it on the reaction.
$^{209}_{83}Bi$
$^{209}_{83}Bi + ^{64}_{28}Ni -- \gt ^{272}_{111}Rg + ^1_0n $
