Checkup on Chapter 3

Bromine atom have $36$ neutrons. How can the bromine atom be represented in the form ${}_{\mathrm{Z}}{}^{\mathrm{A}}\mathrm{X}$?

For each of the six elements aluminium $\left(\mathrm{Al}\right)$, boron $\left(\mathrm{B}\right)$, nitrogen $\left(\mathrm{N}\right)$, oxygen $\left(\mathrm{O}\right)$, phosphorous $\left(\mathrm{P}\right)$ and sulphur $\left(\mathrm{S}\right)$, identify the proton number.

For each of the six elements aluminium $\left(\mathrm{Al}\right)$, boron $\left(\mathrm{B}\right)$, nitrogen $\left(\mathrm{N}\right)$, oxygen $\left(\mathrm{O}\right)$, phosphorous $\left(\mathrm{P}\right)$ and sulphur $\left(\mathrm{S}\right)$, identify the number of electrons in the given elements.

For each of the six elements aluminium $\left(\mathrm{Al}\right)$, boron $\left(\mathrm{B}\right)$, nitrogen $\left(\mathrm{N}\right)$, oxygen $\left(\mathrm{O}\right)$, phosphorous $\left(\mathrm{P}\right)$ and sulphur $\left(\mathrm{S}\right)$, write the electronic configuration.

For each of the six elements aluminium $\left(\mathrm{Al}\right)$, boron $\left(\mathrm{B}\right)$, nitrogen $\left(\mathrm{N}\right)$, oxygen $\left(\mathrm{O}\right)$, phosphorous $\left(\mathrm{P}\right)$ and sulphur $\left(\mathrm{S}\right)$, write the number of outer electrons in its atom.

The outer electrons are also called the _____ electrons

From the six elements aluminium $\left(\mathrm{Al}\right)$, boron $\left(\mathrm{B}\right)$, nitrogen $\left(\mathrm{N}\right)$, oxygen $\left(\mathrm{O}\right)$, phosphorous $\left(\mathrm{P}\right)$ and sulphur $\left(\mathrm{S}\right)$, which elements would you expect to have similar properties and why?

The relative atomic mass of sodium is $23.0$ and that of magnesium is $24.3$. Which of the two elements may exist naturally as single isotope? Explain your answer.