Chemistry Classification of Elements and Periodicity in Properties

The name of the element is derived from its atomic number using the IUPAC nomenclature for elements with Z > 100.
un = 1
nil = 0
enn = 9
So, unnilennium corresponds to the atomic number 109.

On moving left to right in a period.

Acidic character of oxides is increase.

3rd period element oxides.

(i) Acidic character

(ii) Atomic No?

So  have minimum Atomic No

&Z have maxima Atomic No

So correct order is 

 

On moving Left to Right along a period.
Atomic Radius → decreases.
Electronegativity → Increases.
Electron gain enthalpy → Increases.
Ionisation Enthalpy → Increases

i of CaCl? =3. Molality eff=0.15. Molality eff of complex=0.3. [Cr (NH? )? Cl]Cl?

Electron gain enthalpy increases with electro negativity chlorine has higher electron gain enthalpy than fluorine (exception)

In isoelectronic species nuclear charge can be approximated as
Nuclear charge ≈ z / no. of electrons
Al³? Mg²? Na? F? O²? N³?
Nuclear Charge: 13/10 12/10 11/10 9/10 8/10 7/10
Minimum nuclear charge is in N³? and maximum is in Al³?
So order should be
Al³? < Mg? < Na? < F? < O? < N?

Order of I.E:           $\mathrm{N}\mathrm{a}<\mathrm{A}\mathrm{l}<\mathrm{M}\mathrm{g}<\mathrm{S}\mathrm{i}$

$496\mathrm{}\mathrm{}\mathrm{}577\mathrm{}\mathrm{}\mathrm{}737\mathrm{}\mathrm{}\mathrm{}\mathrm{}786$

$\mathrm{}{}_{26}\mathrm{F}\mathrm{e}=\left[\mathrm{A}\mathrm{r}\right]3{\mathrm{d}}^{6}4{\mathrm{S}}^2$

Among Ni, Co, Mn, Fe

Fe having minimum third ionization energy

$\mathrm{C}\mathrm{l}>\mathrm{F}$ (exception)

$\mathrm{S}>$ Se (size effect)

$\mathrm{L}\mathrm{i}>\mathrm{N}\mathrm{a}$ (size effect)