## Chemistry (7th Edition)

$_{24}^{52}Cr$
The number of protons is equal to the atomic number. According to the periodic table, the element with atomic number equal to 24 is Chromium, and it has "Cr" as its symbol. Now, we need to determine the mass number. It is the sum of the number of protons and the number of neutrons: $24 + 28$ = $52$ Now, write the symbol for the element, making the mass number super-scripted and the atomic number sub-scripted. They are both on the left side of the symbol. $_{24}^{52}Cr$