Question

gallium has an atomic number of 31 and a mass number of 70. which table shows the number of protons, neutrons, and electrons in a gallium ion with a +3 charge? (1 point)

Explanation:

Step1: Recall atomic - ion relationships

The atomic number ($Z$) is equal to the number of protons. For gallium, $Z = 31$, so the number of protons is 31. In a neutral atom, the number of electrons is equal to the number of protons. But for a $+ 3$ ion, the atom has lost 3 electrons.

Step2: Calculate number of electrons in the ion

The number of electrons in a neutral gallium atom is 31. For a $Ga^{3 +}$ ion, the number of electrons is $31-3=28$.

Step3: Recall mass - number relationship

The mass number ($A$) is the sum of protons and neutrons. Given $A = 70$ and number of protons $p = 31$, the number of neutrons $n=A - p$. So $n=70 - 31=39$.

Answer:

Protons: 31, Neutrons: 39, Electrons: 28