Each row is independent from the other, so we can use the same method for each one.
Le'ts give a variable for each column:
- S: Symbol
- z: Z (Atomic number)
- a: A (Mass number)
- p: No of Protons
- e: No of Electrons
- n: No of Neitrons
- c: Charge
In the symbol column, the right supercript is the charge, so since the Symbol is:
[tex]S=Mg^{2+}[/tex]The charge is 2+. We write as 2+, but in math we would write as +2, they are the same, but in different notations.
[tex]c=2+=+2[/tex]The atomic number and the symbol are always unique, so each element has always the same atomic number and the other way around too.
From a periodic table, we can see which Element corresponds to which atomic number Z.
On a periodic table, we can see that the atomic number of Mg is 12, so:
[tex]z=12[/tex]Also, the atomic number and the number of protons is always the same:
[tex]\begin{gathered} p=z \\ p=12 \end{gathered}[/tex]The mass number, a, is alwais the number of protons plus the number of neutrons:
[tex]a=p+n[/tex]Since we know that the mass number is 25 in this case, we can calculate the number of protons:
[tex]\begin{gathered} a=p+n \\ 25=12+n \\ n=25-12 \\ n=13 \end{gathered}[/tex]So it checks out with the number on the table.
Each proton has a charge of 1+ and each electron has a charge of 1-. In Math terms, we can say that each proton counts as +1 and each electron counts as -1.
Thus, the charge is the number of protons minus the number o electrons:
[tex]c=p-e[/tex]Since the charge is 2+ and there are 12 protons, we can say:
[tex]\begin{gathered} 2=12-e \\ e=12-2 \\ e=10 \end{gathered}[/tex]So, there are 10 electrons.
Putting altogether, we have:
[tex]\begin{gathered} S=Mg^{2+} \\ z=12 \\ a=25 \\ p=12 \\ e=10 \\ n=13 \\ c=2+ \end{gathered}[/tex]And, by the names:
Symbol: Mg²⁺
Z: 12
A: 25
No. of Protons: 12
No. of Electrons: 10
No. of Neutrons: 13
Charge: 2+
