Question

Fill in the blanks to complete the tableCompleting the first row.

Answer 1

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:

`S=Mg^(2+)`

The charge is 2+. We write as 2+, but in math we would write as +2, they are the same, but in different notations.

`c=2+=+2`

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:

`z=12`

Also, the atomic number and the number of protons is always the same:

`\begin{gathered} p=z \\ p=12 \end{gathered}`

The mass number, a, is alwais the number of protons plus the number of neutrons:

`a=p+n`

Since we know that the mass number is 25 in this case, we can calculate the number of protons:

`\begin{gathered} a=p+n \\ 25=12+n \\ n=25-12 \\ n=13 \end{gathered}`

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:

`c=p-e`

Since the charge is 2+ and there are 12 protons, we can say:

`\begin{gathered} 2=12-e \\ e=12-2 \\ e=10 \end{gathered}`

So, there are 10 electrons.

Putting altogether, we have:

`\begin{gathered} S=Mg^(2+) \\ z=12 \\ a=25 \\ p=12 \\ e=10 \\ n=13 \\ c=2+ \end{gathered}`

And, by the names:

Symbol: Mg²⁺

Z: 12

A: 25

No. of Protons: 12

No. of Electrons: 10

No. of Neutrons: 13

Charge: 2+