Answer
The atomic symbol for that atom is:
$^{42}_{20}Ca$
Work Step by Step
Atomic number = number of protons = 20
1. Find the symbol of the element.
Using the periodic table (Page 100), we can see that the element with atomic number equal to 20 is "Ca".
2. Calculate the mass number:
The mass number is equal to the sum of the number of protons and neutrons.
$Mass$ $number = 20 + 22 = 42$
3. Write the complete symbol.
- Put the mass number in the upper left corner of the symbol, and the atomic number in the lower left corner.
$^{42}_{20}Ca$
