Respuesta :
The notation is actually written in this way (shown in the attached picture). The X is the symbol of the element. So, for potassium, the symbol is K. The A represents the mass number of the isotope. In this case, that would be equal to 39. The Z represents the atomic number of potassium, which is 19. Therefore, the symbol for the isotope is: ³⁹₁₉K

Answer: The atomic symbol of the gibven atom is [tex]_{19}^{39}\textrm{K}[/tex]
Explanation:
The general representation of an isotope is given as [tex]_Z^A\textrm{X}[/tex]
where,
Z = atomic number of the atom
A = mass number of the atom
X = symbol of the atom
We are given:
Mass number = 39
Symbol of the atom = K
So, atomic number = 19
Hence, the atomic symbol of the gibven atom is [tex]_{19}^{39}\textrm{K}[/tex]