Genesis of Periodic Classification

The first $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_1\right)$ and the second $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_2\right)$ ionization enthalpies (in $\mathrm{kJ} {\mathrm{mol}}^{–1}$) and the $\left({\mathrm{\Delta }}_{\mathrm{eg}}\mathrm{H}\right)$ electron gain enthalpy (in $\mathrm{kJ} {\mathrm{mol}}^{–1}$) of a few elements are given below:

Which of the above elements is likely to be the metal which can form a predominantly stable covalent halide of the formula $\mathrm{MX}$ ($\mathrm{X}$=halogen)?

The first $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_1\right)$ and the second $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_2\right)$ ionization enthalpies $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ and the $\left({\mathrm{\Delta }}_{\mathrm{eg}}\mathrm{H}\right)$ electron gain enthalpy $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ of a few elements are given below:

Which of the above elements is likely to be the metal which can form a stable binary halide of the formula ${\mathrm{MX}}_2$, $\left(\mathrm{X}=\mathrm{halogen}\right)$.

The first $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_1\right)$ and the second $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_2\right)$ ionization enthalpies $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ and the $\left({\mathrm{\Delta }}_{\mathrm{eg}}\mathrm{H}\right)$ electron gain enthalpy $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ of a few elements are given below:

Which of the above elements is likely to be the least reactive non-metal.

The first $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_1\right)$ and the second $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_2\right)$ ionization enthalpies $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ and the $\left({\mathrm{\Delta }}_{\mathrm{eg}}\mathrm{H}\right)$ electron gain enthalpy $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ of a few elements are given below:

Which of the above elements is likely to be the most reactive non-metal.

The first $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_1\right)$ and the second $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_2\right)$ ionization enthalpies $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ and the $\left({\mathrm{\Delta }}_{\mathrm{eg}}\mathrm{H}\right)$ electron gain enthalpy $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ of a few elements are given below:

Which of the above elements is likely to be the most reactive element?

The first $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_1\right)$ and the second $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_2\right)$ ionization enthalpies $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ and the $\left({\mathrm{\Delta }}_{\mathrm{eg}}\mathrm{H}\right)$ electron gain enthalpy $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ of a few elements are given below:

Which of the above elements is likely to be the least reactive element.

Assign the position of the element having outer electronic configuration $\left(\mathrm{n}-2\right) {\mathrm{f}}^7 \left(\mathrm{n}-1\right){\mathrm{d}}^1{\mathrm{ns}}^2$ for $\mathrm{n}=6$, in the periodic table.

Assign the position of the element having outer electronic configuration $\left(\mathrm{n}-1\right){\mathrm{d}}^2{\mathrm{ns}}^2$  for $\mathrm{n}=4$.

Assign the position of the element having outer electronic configuration ${\mathrm{ns}}^{\text{2}}{\mathrm{np}}^{\text{4}}$ for $\mathrm{n}=3$.

Use the periodic table to answer the following questions.

(a) Identify an element with five electrons in the outer subshell.

(b) Identify an element that would tend to lose two electrons.

(c) Identify an element that would tend to gain two electrons.

(d) Identify the group having metal, non‐metal, liquid as well as gas at the room temperature.

What are the major differences between metals and non‐metals?

Describe the theory associated with the radius of an atom as it
(a) gains an electron
(b) loses an electron

 How would you react to the statement that the electronegativity of $\mathrm{N}$ on Pauling scale is $3.0$ in all the nitrogen compounds?

Would you expect the second electron gain enthalpy of $\mathrm{O}$ as positive, more negative or less negative than the first? Justify your answer.

Energy of an electron in the ground state of the hydrogen atom is $-2.18\times {10}^{-18}\mathrm{J}.$ Calculate the ionization enthalpy of atomic hydrogen in terms of $\mathrm{J} {\mathrm{mol}}^{‐1}.$ 

Which important property did Mendeleev use to classify the elements in his periodic table and did he stick to that?

What is the basic theme of organisation in the periodic table?