Consider the following orders given below.

(i) S > Se > Te > O (Electron Affinity)

(ii) $N^{-3}>O^{2-}>F^{-}>N{a}^{+}>M{g}^{2+}$  (Ionic Size)

(ii) Fe²⁺ > Fe³⁺ > Fe⁴⁺ (Ionization Enthalpy)

(iv) H < B < P < C < Cl (Electronegativity)

(v) Na⁺ < Mg²⁺ < Al³⁺ (Extent of hydration)

(vi) Li > Na > K > Rb > Cs (Reducing Nature)

(vii) LiF(s) > LiCl(s) > LiBr(s) (Lattice Energy)

If x = number of correct orders

y = number of incorrect orders

then the value of $\left(1+\frac{y}{x}\right)$  is.

s – block and p – block elements together are called as representative elements.

Zn (Z = 30) is a d-block element.

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You can read the classification of elements and periodicity in properties class 11 notes to study class 11 ch3 and score well in class 11th exams and NEET, and JEE exams.

When the elements having similar properties repeat at regular intervals, it is called periodicity in the properties of elements.

Classification of Elements is Necessary because it helps in understanding and remembering elements' properties better, you can understand how elements react or behave, and can guess properties of unidentified or newly discovered elements.