To determine the number of protons, neutrons, and electrons in a gallium ion with a +3 charge, you can use the given information that gallium has an atomic number of 31 and a mass number of 70.
Step 1: Find the number of protons
The atomic number of gallium (Z) is equal to the number of protons in an atom. Therefore, the number of protons in gallium is 31.
Step 2: Find the number of neutrons
The mass number of gallium (A) is equal to the sum of protons and neutrons in an atom. Since the mass number is 70 and the number of protons is 31, subtracting the number of protons from the mass number gives us the number of neutrons. Neutrons = mass number (A) - protons (Z) = 70 - 31 = 39.
Step 3: Determine the number of electrons
In a neutral atom, the number of electrons is equal to the number of protons since positive charges (protons) and negative charges (electrons) balance each other. However, when an atom becomes an ion with a charge of +3, it loses three electrons.
So, the number of electrons in the gallium ion with a +3 charge is 31 - 3 = 28.
Therefore, of the given options, the correct answer is: Particle Number protons 31 neutrons 39 electrons 28.