Question

identify the missing information for each atom or ion. note that the atoms and ions are not necessarily neutral. a se ion has a mass number of 78 and a charge of - 2. determine the number of neutrons, protons, and electrons in this ion. number of neutrons: number of protons: number of electrons: an ion has a mass number of 65, 36 neutrons, and a charge of + 1. identify the element symbol, and determine the number of protons and electrons in this ion. element symbol:

Explanation:

Step1: Recall atomic - related concepts

The mass number ($A$) is the sum of protons ($p$) and neutrons ($n$), i.e., $A=p + n$. For a neutral atom, the number of electrons ($e$) equals the number of protons. For an ion, the charge ($q$) is related to the number of protons and electrons by $q=p - e$. Selenium has an atomic number of 34.

Step2: Calculate for Se ion

For the Se ion with $A = 78$ and $q=-2$.
The atomic number of Se is 34, so the number of protons $p = 34$.
Using $A=p + n$, we can find the number of neutrons $n=A - p$. Substituting $A = 78$ and $p = 34$, we get $n=78 - 34=44$.
Since $q=p - e$ and $q=-2$ and $p = 34$, then $-2=34 - e$, so $e=34+2 = 36$.

Step3: Calculate for the second ion

Given $A = 65$ and $n = 36$. Using $A=p + n$, we find $p=A - n=65 - 36 = 29$. The element with atomic number 29 is copper, symbol Cu.
Since $q = + 1$ and $q=p - e$, then $1=29 - e$, so $e=29 - 1=28$.

Answer:

number of neutrons: 44
number of protons: 34
number of electrons: 36
element symbol: Cu
number of protons: 29
number of electrons: 28